led light bulb experiment

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How to Light an Led Bulb with a Battery

Last Updated: September 30, 2024 Fact Checked

This article was co-authored by wikiHow Staff . Our trained team of editors and researchers validate articles for accuracy and comprehensiveness. wikiHow's Content Management Team carefully monitors the work from our editorial staff to ensure that each article is backed by trusted research and meets our high quality standards. This article has been fact-checked, ensuring the accuracy of any cited facts and confirming the authority of its sources. This article has been viewed 141,663 times. Learn more...

Lighting an LED light bulb up with a battery is a fun experiment you can do to learn about electrical circuits and direct current (DC) electricity. It’s not a practical way to power an actual light source, as regular batteries do not supply enough voltage to power a strong enough light bulb. However, with just a few basic supplies, you can have some fun creating different circuits between a battery and an LED bulb. Once you get the hang of making a simple circuit, you can modify it with things like switches or multiple batteries. You can even try creating a natural battery out of lemons and pieces of metals to demonstrate how acidity works with metal to generate power!

Powering a Bulb with a Household Battery

• You can use a small LED bulb from a flashlight, for example.
• To power a higher voltage light bulb, you would need to string together multiple batteries of 12V or higher, which isn’t safe to do for this experiment as you could get an electrical shock.

The instructions below are for LED bulbs . If you follow those steps using a regular LED, remember they are polarized. Always connect the longest leg to the positive terminal of the battery and the shortest leg to the negative terminal. Else the LED won't light or could be damaged. Do not use a battery with a voltage over 3V, else your LED might explode.

• You can use any standard household battery, such as a AA, AAA, C or D battery, which are all 1.5V batteries.
• You could also just hold the wire in place if you don’t have any electrical tape to temporarily connect them. There is no risk of getting electrocuted by such a low voltage.

Tip : If you want to make a more permanent connection, you can solder the wire in place.

• The bulb lights up because you are making a complete electrical circuit between the positive and negative terminals of the battery and the 2 wires that are inside the light bulb’s base.
• You can also try this experiment with just 1 wire by touching the light bulb directly to 1 of the batteries terminals for 1 of the connections. For example, if you tape an electrical wire between the bottom of the bulb and 1 of the batteries terminal, you can light up the bulb by touching the side of the bulb’s base to the other terminal.

Adding Variations to the Experiment

• A toggle switch is an electrical switch with a knob that you can flip back and forth to turn an accessory on and off. It works by blocking or connecting 2 wires in the electrical circuit.

• Most battery holders have an ON/OFF switch, so you can both carry your experiment around and turn the light bulb on and off easily!

Tip : You could also get a miniature bulb holder to make your experiment even more sleek and portable!

• If you choose to add more light bulbs into the circuit, it doesn’t matter which batteries you connect them to. Since all of the batteries are wired together, they essentially work as a single more powerful battery.
• Keep in mind that if you use too many batteries to power just 1 light bulb, you could blow it out. For example, if you use 6 1.5V household batteries to power a single 3V light bulb, it might blow out. This is not dangerous to you, but the light bulb won't work anymore.

Making a Lemon Battery

• An LED bulb from a small flashlight or a small diode, like from a string of Christmas lights, works well for this experiment.
• The lemon juice inside the lemons provides an acidic solution to create a battery, like battery acid does inside normal batteries.
• Once you try this experiment with lemons, you can experiment with other acidic fruits or even potatoes! [8] X Research source

• This will ensure that the metals you insert inside of the lemons will make contact with as much acidic lemon juice as possible.

• It doesn’t matter how long the pieces of wire and nails are, as long as you can stick them far enough into the lemons and there is still enough sticking up to connect electrical wires to.

• Make sure that the first lemon in the chain has a free piece of copper while the last lemon in the chain has a free nail.

Tip : You could also use electrical wires with alligator clips to make these connections.

• You could tape the wire to the bottom with a small piece of electrical tape if you want to hold it in place.
• If you are using an LED diode that has 2 legs instead of a bottom, just wrap this wire around the longer of the legs.

• If you’re doing this experiment with an LED diode that has 2 legs instead of a side that you can touch the wire to, wrap this wire around the shorter of the legs.
• Since lemon batteries don’t produce a lot of power, the light will probably be pretty dim. You can experiment by using more lemons to make a more powerful battery and see how much brighter you can get the bulb to light up.

Expert Q&A

Things you’ll need, powering a bulb with a normal battery.

• Low-voltage LED bulb
• Household battery
• Copper electrical wire
• Toggle switch
• Battery holder
• Low-voltage LED bulbs
• Household batteries
• Copper electrical wires
• Copper wire
• Galvanized nails

You Might Also Like

• ↑ https://van.physics.illinois.edu/ask/listing/574
• ↑ https://sciencing.com/light-bulb-work-battery-4798212.html
• ↑ https://www.physicsclassroom.com/class/circuits/Lesson-2/Requirements-of-a-Circuit
• ↑ https://www.scienceworld.ca/resource/lemon-battery/
• ↑ https://science-u.org/experiments/lemon-batteries.html
• ↑ https://www.scientificamerican.com/article/generate-electricity-with-a-lemon-battery/

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Lemon Light Bulb Experiment

Did you know that you could easily make a battery at home ?

You can do that by using lemons.

Yes, lemons!

Lemons are sour and carry a lot of citric acid.

Of course, it will not be a powerful battery that can power your refrigerator or a toy car.

But the chemical reaction generates enough energy to power a small LED light and make it light up a bit.

Lemon battery experiments for kids is not hard at all, but you do need a few special equipment.

This lemon science project is a fun science experiment for kids, too.

Let’s start building lemon cells step by step.

How To Use Lemon To Power Light

Learn how to use fruits to generate electricity.

• lemons (You can start with 4. In general, the more you use, the more power can be generated)
• low voltage LED light bulb (you can buy small LED diodes or get one from an old Christmas string light decoration)
• pieces of copper wire
• galvanized zinc nails (the same number as the number of lemons used)
• electrical wires or alligator clips wires
• wire cutter
• adult supervision

Instructions

• Roll and squeeze the lemons a little bit by hand to release the juice inside.
• In each lemon, insert 1 zinc nail and 1 small strip of copper wire. Leave a small section in each one out for the electrical wires to connect.

• In the first lemon, connect the copper to the long leg of the mini LED bulbs. In the last lemon, connect the nail to the shorter end of the LED light (the shorter leg comes out of the flat side of the LED).

Basics of Battery

Batteries are made of two different types of metal suspended in an acidic solution.

In this experiment, copper and zinc (galvanized nails are zinc-plated) are the two metals. The acidic lemon juice serves as the acidic solution.

An electric current is created when the two metals have different tendencies to lose the negatively charged  electrons .

Because zinc metal loses electrons more readily than copper, zinc is the  negative electrode  (anode) and copper is the  positive electrode (cathode). 

When the battery is connected with a LED bulb, it becomes a  closed complete circuit.

The zinc electrode, the LED bulb, and the copper electrode form a complete electronic circuit for the electrical current to go through.

Let's explore more in this classic science experiment. Can you try the experiment again with the following modifications and see what differences they make?

• Use a different types of citrus fruits to make a fruit battery.
• Use other substances such as a vegetable or a cup of tap water as the conducting solution.
• Use different metals as the electrodes.
• Can you make a coin battery using the same principles?
• Can a potato battery work similarly?
• Is a sour flavor in fruits necessary for the battery to work?

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• Electrochemical Cells  by HyperPhysics, Department of Physics and Astronomy, Georgia State University

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Lemon Batteries: Lighting an LED With Lemons

Introduction: Lemon Batteries: Lighting an LED With Lemons

Did you know you can light an LED using fruits and vegetables?

For this experiment, you will need the following materials:

• 4 lemons or potatoes
• 4 galvanized nails
• 4 U. S. copper pennies (minted before 1982 due to the change in copper content) or 4 copper wires
• an LED light
• 5 alligator test leads

Step 1: Creating the Batteries

• Using the knife, slice a penny-sized slit on the right side of your lemon.
• Push the penny far into the lemon, leaving a small area to hook your alligator jumper to. This will be your positive terminal.
• Now, create the negative terminal for your battery. Stick one of the galvanized nails into the left side of the lemon, about 2 inches away from the penny. It is important to have the nail and penny separated. If they touch, it will cause a short.
• Repeat this process until you have 4 complete batteries.

Step 2: Adding the Jumpers

• Make sure the lemons are aligned parallel to one another.
• Attach one of the alligator clips to the nail (negative terminal) on your first lemon.
• Then, run the second jumper wire from the penny (positive terminal) of the first lemon to the nail (negative terminal) in the second lemon. Add the rest of the clips, alternating positive an negative, until all the lemons are attached.

Step 3: Lighting the LED

• Connect the first jumper wire from the nail to the negative connection on the LED. The negative connection on the LED is the shorter wire nearest the base.
• Then, clip the jumper wire from the penny of the last lemon in your chain to the positive connection on the LED. When you complete your circuit, the LED will light up!
• Experiment with different fruits and vegetables to see which one produce the most volts! The higher the voltage, the brighter the light. The average lemon produces just under 1 volt. We need at least 3.5 volts to light up an LED. This is why we need 4 lemon batteries.

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Potato Battery Experiment: Powering a Light Bulb With a Potato

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Did you know you could power a light bulb with a potato? The chemical reactions that take place between two dissimilar metals and the juices in the potato create a small amount of voltage that can power a very small electrical device [source: MadSci].

Follow the instructions below to make a potato battery .

How to Make a Potato Battery

The science behind potato battery experiments, using potato batteries to power other devices.

• One potato (ideally large)
• Two pennies
• Two galvanized nails (zinc-plated nails)
• Three pieces of copper wire
• A very small light bulb or LED light

What You Need to Do:

• Cut the potato in half, then cut a small slit into each half, large enough to slide a penny inside.
• Wrap some copper wire around each penny a few times. Use a different piece of wire for each penny.
• Stick the pennies in the slits you cut into the potato halves.
• Wrap some of the third copper wire around one of the zinc-plated nails and stick the nail into one of the potato halves.
• Take the wire connected to the penny in the half of potato with the nail and wrap some of it around the second nail. Stick that second nail into the other potato half.
• When you connect the two loose ends of the copper wires to the light bulb or LED, it will complete the electrical circuit and light up.

Be careful when handling the wires, because there is a small electric charge running through the wires. Hydrogen gas may also be a byproduct of the chemical reactions in the potato, so don't perform the experiment near open flames or strong sources of heat [source: MadSci].

Batteries store energy for later use, but where does the energy come from? All batteries rely on a chemical reaction between two metals.

In a potato battery, the reaction — between the zinc electrodes in the galvanized nails, the copper in the penny, and the acids in the potato — produces chemical energy.

The potato doesn't produce electricity, but it does allow the electron current to flow from the copper end to the zinc end of the battery.

You can try using multiple potatoes to power other battery-equipped devices, like a clock.

In the battery compartment, connect the potato with a copper coin inside to the positive terminal (marked with a "+") and a potato with a galvanized nail inside to the negative terminal (marked with a "-"). Learn more about how to make a potato clock.

With any potato battery experiment, if your battery doesn't power your device on the first try, you can try increasing the number of potatoes. You can also use other fruits and vegetables to make batteries — lemon, which is highly acidic, is a popular choice.

"Food Batteries." MadSci Network. Mar. 14, 1998. (Sep. 20, 2023). https://www.madsci.org/experiments/archive/889917606.Ch.html

Potato Battery FAQ

How does a potato battery work, can a potato light up a light bulb, why does my potato battery not work, how many amps of energy can a potato battery produce, does using a boiled potato result in more power.

Please copy/paste the following text to properly cite this HowStuffWorks.com article:

Easy LED circuit project - Learn how to make a simple circuit to light a LED.

Posted by Admin / in Energy & Electricity Experiments

A good starter circuit for kids to experiment with is an LED circuit in series on a breadboard. A circuit is in series when the flow of electricity follows a direct line or completes a simple loop. In this example a single Light emitting diode (LED) will be powered by a battery and light up. In order to power an LED without blowing the diode, a resistor is needed to lower the voltage down to an allowable value.

Materials Needed

• 9 Volt battery
• 9 Volt battery terminal
• LED (standard LED, red or green)
• Wire or jumper wires
• 390 Ohm resistor (color code: orange-white-brown)

EXPERIMENT STEPS

Step 1: To create this simple circuit on the breadboard start with a 9 volt battery terminal. Battery terminals can be purchased at any local Radio Shack or online at radioshack.com, mouser.com or your favorite online retailer.

Step 2: Connect the black, (-) negative wire from the battery terminal to a negative power column on the breadboard. A breadboard typically has a positive and negative power rail on each side of the board. In the example photo, the negative power rail on the right side of the breadboard is highlighted in blue. The positive power rail on the breadboard is highlighted in orange.

Step 3: Connect the red, (+) positive wire from the battery terminal to a positive rail on the breadboard.

Step 4: Use a jumper wire to connect the positive side of the power rail to one of the breadboard rows. In the example, row 10 was used for the circuit (see photo).

Step 5: Connect one end of the resistor into the same row as the jumper wire was placed on the breadboard in the previous step. Connect the other end of the resistor into the opposite side of the breadboard using the any row. In the example row 10 was used again. There is no positive or negative side on a resistor so it does not matter which end is connected into the negative column.

Step 6: Complete the circuit by connecting the positive side of the LED into the same row as the second leg of the resistor placed in step 5. The positive leg of a LED is the longer leg, also known as the annode. Place the shorter leg (negative leg) of the LED into the negative power rail. The negative power rail is any opening in the column where the black power wire from the battery was placed in step 2.

Science Learned

An LED is a Light Emitting Diode. The diode produces light from a low amount of voltage. The voltage must be reduced in this circuit since a 9 volt battery is used in this experiment. Standard LEDs are only designed for a maximum voltage between 1.8 volts and 2.2 volts, depending on the color of the LED and manufacturer. In this experiment a solderless breadboard is used to make the electrical circuit. Using a solderless breadboard increases safety for kids since it elimates the need for a hot, soldering iron. An LED circuit is a great starting electronics project for kids since it is simple to build and produces a light, if produced correctly.

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Potato Light Bulb Experiment for Kids

How Can You Make a Potato Flashlight Project?

You may wonder what the link is between a potato, a light bulb and kids. It’s actually a great experiment about making electricity from a potato to illuminate a small light bulb. It teaches kids about the basics of making electricity and how wires allow electricity to move from one place to another in a complete circuit.

Understanding a Potato Battery

It is likely most kids will find it difficult to believe that a simple potato can make electricity to power a light bulb. However, the explanation is relatively simple. A potato contains sugar, water and acid. Certain types of metals – particularly copper and zinc – react with the potato when they are inserted inside. The metals effectively become electrodes, one positive and the other negative, and electrons flow between the metals inside the potato, making a small electric current. You can tap into the electricity by connecting wires from the electrodes to a light bulb to form a circuit. The electrons flow from the positive electrode to the light bulb and back to the negative electrode. The electrical current passing through the light bulb is enough to make it illuminate.

Making a Potato Battery

Put a 3-inch copper nail and a 3-inch zinc nail into the potato about 1 inch apart from each other. Push the nails to a depth of about 1 1/2 inches. Cut two 6-inch strips of very thin wire and remove 1/2 inch of plastic from the ends of the wire strips. Wrap one of the ends of each wire strip around the top of each nail. Put the opposite ends of the wire onto the two terminals on a 1-volt LED bulb. The LED illuminates, but it’s rather dim because very little electricity is made.

Increase Voltage

Use another potato to demonstrate how you can increase the voltage by wiring a second potato into the circuit to create a series. A series circuit increases the output voltage. For example, if one potato produces 1 volt, two potatoes produce 2 volts.

Put another copper and zinc nail into the second potato. Cut another 6-inch strip of wire. Remove the wire from the zinc nail in the first potato and wrap it around the zinc nail in the second potato. Wrap one end of the third strip of wire you have just cut around the zinc nail in first potato and the opposite end around the copper nail in the second potato. Place the opposite end of the wire from the copper nail in the first potato onto the LED bulb terminal and the opposite end of the wire from the zinc nail in the second battery onto the other LED terminal. The LED is much brighter than before.

Using Different Potato Varieties

Now that the kids know how potatoes can make electricity, repeat the experiment using different varieties. Some potatoes have higher water content, while some have more sugar. These different constituents affect the amount of electricity a potato can produce. Make a potato battery from each variety and record how bright the light is from each potato on a scale of one to five, to see which type of potato makes the best battery.

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• PhysLink: How can a Potato be used to Light a Light Bulb?; Lee Ellen Benjamin, MA

About the Author

James Stevens has been writing articles for market research companies in the U.K. since 1990. He has written various country profiles for inclusion in comprehensive market reports including Vision One Research and Investzoom Market Research. Stevens holds a General Certificate of Education from Chelmsford College of Further Education.

Find Your Next Great Science Fair Project! GO

Lemon Battery Science Experiment

We love building circuits around here. From our very first Circuit Bugs creation to Potato Batteries , we have had a lot of fun over the years experimenting with low voltage experiments and electricity in our elementary science lessons. With summer here, that means lemons and lemonade. It also means it was time for us to create the favourite lemon battery science experiment.

How to Build a Lemon Battery

What you will discover in this article!

Disclaimer: This article may contain commission or affiliate links. As an Amazon Influencer I earn from qualifying purchases. Not seeing our videos? Turn off any adblockers to ensure our video feed can be seen. Or visit our YouTube channel to see if the video has been uploaded there. We are slowly uploading our archives. Thanks!

We often talk around here about the energy in nature and in everything around us. When we can power a light bulb with that energy it suddenly makes it very real for my kids. That energy isn’t just some crazy weird thing that I babble on about, it is this very real power that is showing itself right in front of them.

Normally our circuits are powered by batteries, but one day I convinced the kids we could power a light bulb with nothing but a potato. You should have seen the looks on their faces! Serious side eye was thrown my way.

Then, once they stopped straining their eyeballs, we built a potato battery and it worked! These kinds of science experiments for kids really stick with them. Why? Because it makes things real that they can’t otherwise see. Like the energy in our food.

Plus, when a child starts a science experiment with serious doubts, yet still achieves success, it powers up their curiosity!

So when we went grocery shopping and there was a huge pile of fresh, juicy looking lemons on display the kids asked to buy some for lemonade, but I knew we had another science experiment in our future.

Note: These food based battery experiments produce low voltage and are safe for older, responsible children to do under adult supervision.

How to Build a Lemon Battery Video

Watch as I go through the whole experiment step by step in our video tutorial. If you can’t see the video, please turn off your adblockers as they also block our video feed. Alternatively, you can also find this video on the STEAM Powered Family YouTube Channel .

Lemon Battery Materials

Lemons! You need at least 4 to create enough energy, but why not grab extras and experiment? Copper anode strip plates Zinc anode strip plates Alligator clips with wires (2 per cell, so minimum 8 if you are creating a 4 cell battery) LED light diodes Multimeter Knife and cutting board

Copper and Zinc plates are invaluable in our science experiments, but if you don’t have them, you can use copper pennies (the older the better) and zinc plated (aka galvanized) nails. Copper wire can also be used, and a search of your local hardware store is likely to produce other copper and zinc items you could test in your experiment.

The first step is to roll the lemons. Just like you would if you were about to eat or juice them. This releases the juices inside and we want our lemons as juicy as possible.

Start with one lemon and make a small cut through the peel on either end. It is very important that you place these far enough apart that the electrodes don’t touch.

Insert a copper plate on one side and a zinc plate on the other side.

Now using your multimeter test your energy levels.

We have energy!

Now it is time to start adding more cells (lemons) to our battery.

Repeat the above steps on a second lemon. Once you are finished use an alligator clip to connect the zinc plate on the first lemon to the copper plate on the second lemon.

Test your energy level with 2 cells (you will test by touching the copper plate on the first lemon and zinc on the second). Remember you are completing the circuit.

Now repeat the steps to add a third and fourth cell.

At 4 cells we are now registering more energy than 2 AA batteries, which we tested in our Potato Cell experiment .

Now it is time to hook up our light bulb!

Voila! Light!

The goal of making a lemon battery is to turn chemical energy into electrical energy, creating enough electricity to power a small LED light. You can also use limes, oranges, potatoes , pumpkins/squash , or other acidic foods. 

How A Lemon Battery Works

How does a lemon battery work? The science behind how food can power a light bulb is really fascinating. Food has energy. With a lemon battery we are capturing that energy and using it to light up a LED. To do this we need electrodes to capture the energy from our electrolyte.

The zinc and copper plates are called electrodes, and the lemon juice is our electrolyte.

All batteries have a “+” (known as the cAll batteries have a “+” (known as the cathode) and a “-” (known as the anode) terminal. In our lemon battery, the copper plate is our positive cathode and the zinc plate the negative anode. The zinc metal (our negative anode) reacts with the acidic lemon juice (mostly from citric acid) to produce zinc ions (Zn2+) and electrons (2 e-).

Electric current is created by the flow of atomic particles called electrons. Conductors are materials that allow electrons (and the electrical current) to flow through them. Electrons flow from the negative to the positive terminal.

So in our experiment electrons are flowing from our zinc plate, through the lemon juice to the copper plate. From there it goes into our alligator clip, along the wire, into the zinc plate on the next lemon, where it picks up more energy as it travels through that cell. It continues on, building energy with each additional cell we add. Until finally we have enough voltage to power a light bulb.

Volts (or voltage) is a measurement of the force moving the electrons through our lemon battery.  The higher the voltage the more power the battery has, but higher voltage also means greater danger. Always remember to be careful and safe around electricity. Thankfully our lemon battery is very low voltage.

Troubleshooting

There are a number of things that can cause issues with your Lemon Battery.

First, make sure none of your electrodes are touching anything other that lemon and alligator clips. Also, ensure your alligator clips are placed near the peel of the lemon.

Did you roll your lemons? You want them juicy for this experiment to work.

Did you mix up any of your connections? Remember you always want to link “+” to “-“. On an standard LED light bulb the longer pin is the positive connection.

Does your LED bulb work? Test it on a coin battery to ensure your bulb works. It may be you have a faulty bulb.

Another area that can cause problems is the quality of your copper and zinc. You want your copper and zinc to be as pure as possible so it can conduct the electrons without any interference. This is one of the reasons I suggest investing in proper plates, so you know the quality of your materials when conducting experiments.

Finally, these food based batteries dimly light up the LED. If you hook your LED up to a regular battery, it will glow much brighter.

More Fruit Battery Experiments

So now we have made both a lemon battery and a potato battery, which one is better? Both were able to light up our LED light bulbs, so in that sense they are both successful. However, the potato battery was definitely a lot more work. So if you are looking for a quicker experiment, the lemon battery is faster and easier. However, both have significant opportunities for learning and would make great science fair projects. Why not do both yourself and see what you think?

And in the fall, don’t forget to make a battery with pumpkins and squash ! The concept is similar to Lemon Batteries but with a Autumn/Halloween theme.

Want to dig in more? Try this experiment with other citrus fruit such as oranges or lime or grapefruit. You can also combine a variety of fruits to see which combination makes the best fruit battery.

How to Reuse Lemon Battery Cells

This lemon science project is a ton of fun but once you are done, what can you do with the lemons? It seems like such a waste to throw them out. We have two really cool projects to do next with your lemons!

Check out the gorgeous lemon volcano we created here after building our lemon batterie s!

Another great project with these lemons is to make Lemon Oobleck for a fun, summery sensory project.

More Electricity Experiments

5 Days of Smart STEM Ideas for Kids

Get started in STEM with easy, engaging activities.

Lemon Battery Experiment

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Have you ever tried the lemon battery experiment? Well if not, it’s time to give it a try!  Here I will show you how a lemon can light up a light bulb or even a small clock!

Lemon batteries are an experiment that has been around for a while, but it is always such a delight to see it in action! Kids just love it. I’ll show you how to build your own lemon battery today. This is an awesome science project for kids, or great for any STEM project!

Science has always been more of a boy field, but more and more girls are becoming increasingly interested in science. Did you know that only 1 in 1,000 girls pursue a STEM career? Hopefully we can soon change that! This is a fun way to start them on the path and get young girls interested.

My daughter loves learning about all kinds of science fields from nature to electricity to coding, but I would say leans more toward artistic careers for the future. However, I love doing science experiments with her to help her see how great science can be. This lemon battery is a great one to start with if you have kids expressing an interest in STEM projects.

STEM, if you are not familiar stands for Science, Technology, Engineering, and Math. We received a free STEM themed box from Green Works teaching us how to create this project, but it is easy to recreate on your own!

Supplies to Make a Lemon Battery:

Small LED Light Bulb  (LED= light-emitting diode) 4 Lemons Alligator Clips Zinc nails, a zinc strip or a galvanized nail (can be easily found at a hardware store) Copper Wire, a copper strip, or copper coin- pennies work great

Try also this fruit powered digital clock !

How to Make a Lemon Battery:

The first step is to roll the lemons on a hard surface to break apart the juice pockets in the lemon cells. Get ready to make some lemon power!

In each of the 4 lemons, make 2 small slits with a knife and place a nail in one side and piece of copper wire or a copper penny on the other side.

Connect the nail on the first lemon to the copper wire or copper pennies on the second lemon. Continue this and connect them all in a circle except for the first and last ones.

On these two last lemons, connect one alligator clip to a nail and to part of the LED bulb and the other to a copper wire and to the other part of the light. This will complete the electrical current and light up the light!!  Be sure to match up the positive electrode and the negative electrode correctly. If you don’t the battery will not work properly.

Connect a multimeter to test the voltage. Will the volts be higher if you make the chain longer and add more lemons?

How Does the Lemon Battery Work?

A battery generates electricity by passing electrons between two. different metals (one that is positively charged and one that is negatively charged). These electrons create an electrical current as they pass through a solution with molecules that will move the charged particles back and forth between the two different metals. In this instance, the solution is the lemon juice.  

The lemon battery is made with two different metals: copper wire (you could also do it with a penny) and a galvanized (or zinc coated) nail. The lemon has citric acid in the juice. The zinc and copper are the electrodes and the lemon juice is the electrolyte. A chemical reaction happens that is called oxidation-reduction, where there is a transfer of electrons. The zinc is oxidized inside the lemon, some of its electrons are transferred to the copper to reach a lower energy state. The energy released creates the power, lighting up the bulb. The wires allow this transfer of energy.

Try a different kind of fruit battery~ Do other citrus fruits work, too?  Will limes, grapefruit or oranges work just as well?

Did you enjoy this lemon science project?  Try some of my other fun science experiments and activities!

Check out some more of our cool STEM  activities & Science Fair Projects .

See More Electricity Experiments:

Science Art: Conductive Paint Circuits Christmas STEM: Gingerbread House Paper Circuits EASY Play Dough Circuits Building Electric Circuits: STEM Challenge Cards Origami Firefly Paper Circuits

Former school teacher turned homeschool mom of 4 kids. Loves creating awesome hands-on creative learning ideas to make learning engaging and memorable for all kids!

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Very awesome! I think my 8 year old would enjoy making a battery out of lemons!

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24 Shockingly Fun Electricity Experiments and Activities for Kids

Play dough circuits, LED magic wands, and more!

Electricity is all around us, so we tend to take it for granted. It’s a fascinating subject for kids, though, so they’ll love these electricity experiments and activities. You may need to invest in a few simple supplies for some of these activities, but you’ll be able to reuse them for multiple activities year after year. The hands-on experience kids will get makes the extra effort worthwhile.

1. Start with an anchor chart

Static electricity is most kids’ intro to this concept, and it leads nicely into electrical energy and circuitry. These colorful anchor charts help you teach both.

Get tutorial: Anchor chart about electricity and electricity anchor chart

2. Bend water with static electricity

Most static electricity experiments are quick and easy enough for anyone to try at home. This is a great example: Charge a comb by rubbing it against your head, then use it to “bend” a stream of water from a faucet.

Get tutorial: Water balloon experiment

3. Separate salt and pepper using a magic spoon

This static electricity experiment works because pepper is lighter than salt, which makes it quicker to jump to the electrically charged plastic spoon. So cool!

Get tutorial: Salt and pepper experiment

4. Move a bubble using a balloon

Balloons are a fun way to teach about static electricity. Combine them with bubbles for a hands-on activity students will really love.

Get tutorial: Bubble experiment

5. Flap a (paper) butterfly’s wings

Speaking of balloons, try using them to help a butterfly flap its tissue paper wings. Little ones’ faces light up when they see the butterfly come to life.

Get tutorial: Butterfly wing experiment

6. Make jumping goop with static electricity

Kick your static electricity experiments up a notch by mixing a batch of cornstarch “goop,” then making it “jump” toward a balloon. Amazing!

Get tutorial: Jumping goop experiment

7. Assemble circuits from play dough

When you’re ready to explore electrical energy, start with play dough circuits. You’ll need a battery box and mini LED lights. Mix up your own batches of insulating and conducting play dough using the info at the link.

Get tutorial: Play dough circuit experiment

Buy it: Battery box and clear LED lights at Amazon

8. Create a classic potato clock

A potato clock is an impressive way to kick off or end a unit on electricity. Your students will never look at potatoes the same way again.

Buy it: Potato Clock experiment kit

9. Find out if water conducts electricity

We’re always telling kids to get out of the water at the first sign of a lightning storm, so use this demo to help them understand why. You’ll need alligator clip wires, mini LED bulbs, and button cell batteries.

Get tutorial: Water electricity experiment

Buy it: Alligator clip wires , mini LED bulbs , and button cell batteries at Amazon

10. Whip up wizard wands

Lumos! If your kids are fascinated by Harry Potter and the world of magic, they’ll love this electricity project that turns ordinary sticks into light-up wands! Learn how it’s done at the link.

Get tutorial: Wizard wand project

11. Play a DIY steady-hand game

Electricity experiments like this one are perfect for exploring the idea of open and closed circuits. Plus, kids will have so much fun playing with them.

Get tutorial: Steady-hand game

12. Copper-plate coins using electricity

We all know electricity lights up a room and powers phones, computers, and even cars. But what else can it do? This electroplating experiment is a real jaw-dropper. 

Get tutorial: Copper plate coins experiment

13. Create an index card flashlight

This DIY flashlight really turns on and off! It only takes index cards, aluminum foil, mini LED bulbs, an button cell batteries.

Get tutorial: Index card flashlight

Buy it: Mini LED bulbs and button cell batteries at Amazon

14. Twirl some homopolar dancers

These sweet little twirling dancers are a fantastic demonstration of a homopolar motor. In addition to basic AA batteries, you’ll need neodymium magnets and copper wire.

Get tutorial: Homopolar dancers

Buy it: Neodymium magnets and copper wire at Amazon

15. Build multiple circuits

Create more than one circuit using play dough to create a series. The positive leg of the LED is near the battery terminal. Since the battery can only push the electricity one way, you can create a circuit of two or more to create a larger circuit.

Get tutorial: Series circuit experiment

16. Make a coin battery

Use a stack of coins (the more coins you use, the more electricity produced) to make a battery.

Get tutorial: Coin battery

17. Make an electromagnet

Make an electromagnet, or a magnet that uses an electric field, by wrapping wire around an iron nail and running current through the wire. An electric field is created around the nail and, sometimes, the nail will stay magnetized even when the coil is removed.

Get tutorial: Electromagnet project

18. Create a pencil resister

Learn about how resisters control the amount of electricity that flows through a circuit. Use pencils (a great way to use those old stubby pencils that are sharpened at both ends) as part of the circuit, and watch the brightness of the build change when the resistance in the circuit changes.

Get tutorial: Pencil resister project

Buy it: AA batteries , battery holder , LED light bulbs , and alligator clips at Amazon

19. Find out what conducts electricity

Figure out what objects are made of material that conducts or does not conduct electricity. Collect common objects such as a key, chalk, wood, and/or candle. Then, test each object by putting it between a battery and a light bulb and touching foil to the base of the bulb. If the bulb lights up, the object conducts electricity!

Get tutorial: What conducts electricity? experiment

Buy it: AA batteries and LED light bulbs at Amazon

20. Create electric paint

Use electric paint to create a circuit and light up a painting with batteries and LEDs. You will need a multimeter for this project (here’s how to use a multimeter ).

Get tutorial: Electric paint project

Buy it: Multimeter , electric paint , 9-volt batteries , LED light bulbs , and alligator clips at Amazon

21. Create an electromagnetic train

Show the connection between electricity and magnetism by creating a train with a battery and some neodymium magnets. One note: This is a project for older students who have close adult supervision, as neodymium magnets are very strong.

Get tutorial: Electromagnetic train project

Buy it: Neodymium magnets at Amazon

22. Create an electroscope with a soda can

An electroscope detects the presence of an electronic charge. Create a basic but effective electroscope with a soda can, insulation tape, aluminum foil, and a Styrofoam cup. Put it near various surfaces and see what happens.

Get tutorial: Soda Can Electroscope

23. Turn dirt into a battery

Electricity can even conduct in dirt. Create a dirt battery with galvanized steel screws (very important), an ice cube tray, copper wires, and soil. Make it more interesting by putting lemon juice or vinegar in the dirt.

Get tutorial: Dirt Battery Experiment

Buy it: Copper wire and galvanized screws at Amazon

24. Lemon battery

Use a lemon to create a battery with coins and a multimeter. It’s a great way to show students how literally anything can be a conductor of electricity.

Get tutorial: A Simple Lemon Battery

Buy it: Multimeter at Amazon

Love these electricity experiments and activities? Check out Easy Science Experiments Using Materials You Already Have On Hand .

Plus check out turn muggles into wizards with harry potter science experiments ..

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What Is Inquiry-Based Learning? A Guide for Educators

Learn the ins and outs of this emergent student-centered curriculum. Continue Reading

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Potato Light Bulb Experiment

Explore how potatoes can power a light bulb! This potato light bulb experiment is a fantastic way to introduce kids to electricity and circuits. Follow the printable step by step instructions to set up a potato battery for an engaging addition to any STEAM curriculum.

Explore the physical sciences with this simple circuit activity for kids. Make sure to get the free printable instructions further below! It is perfect for 4th grade , 5th grade , and 6th grade science .

• 2-3 large potatoes
• 2 copper wires
• 2 galvanized nails (zinc-coated)
• 1 small LED light bulb (a low voltage one)
• 2 alligator clips
• A knife (for adult use only)
• A multimeter (optional for measuring voltage)

Instructions:

STEP 1. If the potatoes are too large, cut them in half. You’ll need two halves per potato. If they are a manageable size, you can use them whole. Make sure each potato has a flat surface to rest on.

STEP 2. Insert one galvanized nail into each potato. Push it in deep enough to stay secure but not go through.

STEP 3. Insert one copper wire into each potato, ensuring it’s not too close to the nail. The wire and nail should be about 1-2 inches apart.

STEP 4. Using an alligator clip, connect the first potato’s copper wire to the second potato’s nail. If you’re using more than two potatoes, continue connecting them in this series pattern: copper wire to nail, and so on.

STEP 5. Next, set up the light bulb. Connect the free copper wire from the first potato to one terminal of the LED light bulb using an alligator clip.

STEP 6. Use the second alligator clip to connect the free nail from the last potato to the other terminal of the LED light bulb.

Choose the Right Bulb: Ensure your LED light bulb is low voltage; otherwise the potatoes may not generate enough power.

Once all connections are secure, the LED light bulb should light up. If it doesn’t, check all connections to ensure they are tight and correct.

Optional – Measure the Voltage: If you have a multimeter, you can measure the voltage your potato battery produces. Connect the probes to the nails and wires to see the electrical output.

Free Potato Light Bulb Printable Instructions

Grab free instructions to add this potato light bulb project to your STEM lesson plan!

How Does It Work?

This potato battery is a simple way to demonstrate how a chemical reaction can produce electricity.

Your circuit consists of a potato, which acts as an  electrolyte , a substance that contains free ions and conducts electricity. Copper wire (or a coin) and a galvanized nail (zinc-coated) are used as  electrodes . Alligator clips connect the metals to complete the circuit. A light bulb or LED shows that electricity is being produced.

The potato contains phosphoric acid, which interacts with zinc and copper. The zinc undergoes a chemical reaction (oxidation) in which it loses electrons, and these electrons flow through the wire from the zinc nail to the copper wire.

As the electrons flow from the zinc to the copper, they pass through the wire and light up the bulb or LED.

In the potato, positively charged hydrogen ions move toward the copper electrode, gaining electrons (reduction). This completes the circuit, allowing continuous electron flow.

A potato battery is a fun demonstration of the principles of electricity and shows how chemical energy can be converted into electrical energy.

Experiment Further: Try using different fruits or vegetables like lemons or apples to see if they work as a battery and produce a similar or different voltage.

More Electricity Experiments For Kids

• Make a Lemon Battery
• Build a Simple Robot Car
• Power a Clock With A Pumpkin
• Make an Electromagnet

Also explore…

• Static Electricity
• Light Energy
• Potential & Kinetic Energy
• Chemical Reactions

STEM Resources To Get You Started

Here are a few resources that will help you introduce STEM more effectively to your kiddos or students and feel confident yourself when presenting materials. You’ll find helpful free printables throughout.

• Engineering Design Process Explained
• What Is An Engineer?
• Engineering Words
• Real World STEM
• Questions for Reflection (get them talking about it!)
• BEST STEM Books for Kids
• 14 Engineering Books for Kids
• Jr. Engineer Challenge Calendar (Free)
• Must Have STEM Supplies List
• Join us in the Club

Printable STEM Pack for Kids

80+ Doable Engineering Projects in one convenient pack!

• Full instructions with sample images
• Activity-specific instruction sheets
• Data Collection Sheets
• Questions for Reflection
• Architecture Building Cards: Try the tallest tower challenge
• Bridge Building Cards: Explore different types of bridges to build your own.
• Paper Chain STEM Challenge: Who can make the longest chain? Great icebreaker or quick challenge!
• 3 Little Pigs Architectural Pack: Design a house that won’t blow away!
• Great marshmallow challenge: A classic challenge kids love!
• Real-world STEM challenge lesson but don’t know where to start? Our easy-to-follow template shows the steps!
• What’s the difference between a scientist and an engineer?
• Crossword and word search with engineering vocabulary.
• Engineering vocabulary cards
• Design a one-of-a-kind invention and write about it with this 5-page activity!

Subscribe to receive a free 5-Day STEM Challenge Guide

~ projects to try now ~.

Battery and Bulb Experiment for Kids

Use this battery and bulb experiment to teach kids about electrical circuits. For each pair of students, you’ll need a 1.5-volt light bulb, a battery, and a strip of aluminum foil. To promote inquiry, just tell them to light the bulb!

Ms. Sneed Uses a Battery and Bulb Experiment to Promote Inquiry

Our favorite fourth grade teacher, Ms. Sneed, grinned. “You’re going to love this physical science experiment!” she told her student teacher, Mr. Grow. “The first activity in our electricity unit involves batteries and bulbs. It’s super simple. We give each pair of students a light bulb, a battery, and a strip of aluminum foil. Then we ask them to find as many ways as possible to light the bulb.”

“Isn’t that too easy?” asked Mr. Grow.

“Not at all. You’ll see. Help me gather the materials. This fun little activity will scaffold kids to simple circuits , conductors and insulators , and finally, series and parallel circuits .”

Mr. Grow headed to the science cabinet. After locating the bin labeled “electricity,” he began digging out the materials.

“Wait just a minute,” laughed Ms. Sneed. “We need batteries and bulbs with similar voltage.”

“Huh?”

“We’ll use these rechargeable AA batteries. If you look closely, you’ll see that they have 1.2 volts. If we don’t have enough of those batteries, we can also use other AA, A, C, or D batteries. Although they’re different sizes, they all have 1.5 volts.”

Mr. Grow looked surprised. “I thought the bigger batteries were stronger.”

“Nope. And we need bulbs with similar voltage. For example, this bulb works in a lamp. It has 120 volts. Obviously, a 1.5-volt battery would not light it.” She pulled out a small package of 1.5-volt light bulbs. “But it will light these.”

Mr. Grow still looked a little confused. “If you try it yourself,” Ms. Sneed said, “you’ll understand the concept so much better. Why don’t you join a lab group tomorrow? Then you can do the experiment with the kids.”

Try, Try Again – Teaching Persistence Through Inquiry

The following day, Mr. Grow sat beside a fourth grade student named Marissa. “This is easy,” she said. “We just connect the light bulb to the battery with the aluminum foil.”

Marissa held one end of the foil on the positive end of the battery and the other on the metal tip of the bulb. Unfortunately, nothing happened. “What?” she cried. “Our bulb is broken. Ms. Sneed! Our bulb doesn’t work. Please give us another one.”

Mr. Grow noticed that several kids were calling to Ms. Sneed for new bulbs or batteries. She just smiled and nodded. “Hmm. I’m sure they work. Before the lab, I tested them all. Keep experimenting.”

Marissa huffed in annoyance. “Why won’t she just tell us? Can you give me a hint, Mr. Grow?”

“Sorry, Marissa, I don’t even know myself. Let’s keep trying.”

Marissa decided to hold one end of the foil on the positive end of the battery and one on the negative end. “Ouch! That burns!” she moaned.

Ms. Sneed evidently heard Marissa’s cry. “If it’s hot, let go!” she told the class.

“Hey, Marissa,” said Mr. Grow. “Heat is energy. That tells us something is happening. Let’s try setting the light bulb on top of the foil.” Still nothing happened.

Now Mr. Grow was getting frustrated with the battery and bulb experiment. But Ms. Sneed insisted that they keep trying. Inquiry learning really required persistence!

Then, as Mr. Grow held the bulb on top of the positive end, Marissa connected one end of the foil to the negative end. As she was trying to touch the other end to the tip of the bulb, the foil brushed the side of the bulb — and it lit!

Finding Additional Solutions

Around the room, Mr. Grow could hear shouts. “We did it!” students yelled. As he looked at the pairs, he could see some with lit bulbs (and faces) and others still working.

“Once you find a solution,” Ms. Sneed said, “draw it on your lab sheet . Then try to find more. I’ll tell you that there are at least four configurations that will light the bulb.”

Mr. Grow noticed that Ms. Sneed was now moving to each group to ensure that they found at least one solution. Once they experienced success, she quickly moved away to let them find more configurations on their own.

Ms. Sneed’s Class Makes Generalizations About the Battery and Bulb Experiment

“Let’s finish up!” Ms. Sneed called.

A few minutes later, she called everyone to attention. “I’d like to make a classroom display.” She held up a paper light bulb and a paper battery. “Raise your hand if you’d like to share a configuration that worked. Then I’ll call you up here to show it. After you arrange the battery and bulb, we’ll glue it to this construction paper. Finally, you’ll draw a line with with a marker to show how the aluminum foil connected them.”

Mr. Grow watched as Ms. Sneed called kids to the front of the classroom. She asked the other students to confirm whether it would work or not. Soon, six solutions* hung on the wall.

“Now we’ll make a generalization,” said Ms. Sneed. “Who can explain how to light a bulb with a battery and a piece of aluminum foil?”

After a few minutes of wordsmithing, Ms. Sneed typed their statement and hung it with their generalizations:

• One end of the foil must touch one end of the battery.
• The other end of the foil must touch one end of the battery.
• The other end of the foil must touch the side or tip of the bulb.
• The side or tip of the battery that isn’t touching the foil must touch the other end of the battery.

Mr. Grow smiled. Finally, he understood how to make a circuit. More than that, he understood Ms. Sneed’s motivation for using inquiry in her science class.

Ms. Sneed Explains the Light Bulbs and Batteries Experiment

“We’re not done yet!” exclaimed Ms. Sneed.

She picked up a marker and drew one configuration from the day’s experiment. “This is an electrical circuit . Remember when we learned about atoms? Well, in a circuit, electrons flow from atom to atom. This is called current electricity .

“The battery supplies the force for this current. It has two electrodes, the anode and cathode.” Ms. Sneed pointed to the negative and positive ends of the battery. “When the foil is attached to both, chemical reactions occur inside the battery. One reaction causes the anode to become negatively charged. The other causes the cathode to become positively charged. This forces electrons to flow through the foil from the anode to the cathode.”

Mr. Grow listened with interest. Evidently, Ms. Sneed had reviewed the process and vocabulary prior to the lesson. She was definitely not flying by the seat of her pants.

“However,” Ms. Sneed continued, “our circuit also has a resistor: this light bulb.” She pointed to the drawing and picked up her marker. “The electrons flow from the anode through the foil then to the side of the bulb.” Ms. Sneed traced the path. “If you look closely, you’ll see that the filament inside the bulb is attached to the side. It continues through the filament and out through the tip. Then it goes back into the battery.”

“The path must be closed,” Ms. Sneed said. “It’s like your circulatory system. Your heart forces your blood to move through your veins and arteries in a continual cycle.”

Mr. Grow sighed. When he watched Ms. Sneed teach, he realized that even the smallest details helped kids understand. Using an analogy drove the concept home. With practice, he hoped he could become a master teacher too.

LEDs and OLEDs

S mall lights with big potential: light emitting diodes & organic light emitting diodes Commercial History (1960s - Today) Introduction & Statistics   How They Work (LED) OLEDs - Introduction and How They Work Inventors and Developments (LED) Inventors and Developments (OLEDs) Introduction: The LED is a light source which uses semiconductors and electroluminescence to create light. There are two major kinds of light emitting diodes: LED and OLED . The LED is different than EL lamp in that it uses a small semiconductor crystal with reflectors and other parts to make the light brighter and focused into a single point. The OLED is very similar to the EL lamp in design, using a flat sandwich of materials. It is different than the LED and EL lamp in that it uses organic (carbon) molecules in the layer that emits light. All credits and sources are located at the bottom of each lighting page Our video on LEDs and OLEDs, click the bracket icon on the lower right to expand size:   LEDs Currently the LED lamp is popular due to it's efficiency and many believe it is a 'new' technology. The LED as we know it has been around for over 50 years. The recent development of white LEDs is what has brought it into the public eye as a replacement for other white light sources. Common uses: indication lights on devices, small and large lamps, traffic lights, large video screens, signs, street lighting(although this is still not widespread) Large LED array designed for use as a street lamp. A massive aluminum heat sink is needed with the high wattage LEDs

Advantages: -Energy efficient source of light for short distances and small areas. The typical LED requires only 30-60 milliwatts to operate -Durable and shockproof unlike glass bulb lamp types -Directional nature is useful for some applications like reducing stray light pollution on streetlights Disadvantages: -May be unreliable in outside applications with great variations in summer/winter temperatures, more work is being done now to solve this problem -Semiconductors are sensitive to being damaged by heat, so large heat sinks must be employed to keep powerful arrays cool, sometimes a fan is required. This adds to cost and a fan greatly reduces the energy efficient advantage of LEDs, it is also prone to failure which leads to unit failure -Circuit board solder and thin copper connections crack when flexed and cause sections of arrays to go out -Rare earth metals used in LEDs are subject to price control monopolies by certain nations -Reduced lumen output over time

LEDs create light by electroluminescence in a semiconductor material . Electroluminescence is the phenomenon of a material emitting light when electric current or an electric field is passed through it - this happens when electrons are sent through the material and fill electron holes. An electron hole exists where an atom lacks electrons (negatively charged) and therefore has a positive charge. Semiconductor materials like germanium or silicon can be "doped" to create and control the number of electron holes. Doping is the adding of other elements to the semiconductor material to change its properties. By doping a semiconductor you can make two separate types of semiconductors in the same crystal. The boundary between the two types is called a p-n junction. The junction only allows current to pass through it one way, this is why they are used as diodes. LEDs are made using p-n junctions. As electrons pass through one crystal to the other they fill electron holes. They emit photons (light). This is also how the semiconductor laser works.

Above: A laser also creates light, but through a different construction. Read more about semiconductor devices used in electronics here.

To understand p-n junctions and semiconductors better you will need to invest a good amount of time in a lecture, it is not a simple phenomena and far too lengthy to cover here. See a 59 minute introduction lecture to solid state (semiconductors) here .

Phosphors are used to help filter the light output of the LED. They create a more pure "harsh" color.

Engineers had to figure out how to control the angle the light escapes the semiconductor, this "light cone" is very narrow. They figured out how to make light refract or bounce off all surfaces of the semiconductor crystal to intensify the light output. This is why LED displays traditionally have been best viewed from one angle.

Above: A "Jumbotron" or full color LED display. This type of display is only usable for large area applications and decorative backgrounds in small spaces. The human eye can only effectively perceive the image at more than 6 meters distance. The tricolor array is arranged in the close-up at the top right.

Red and Infrared LEDs are made with gallium arsenide Bright Blue is made with GaN - gallium nitride White LEDs are made with yttrium aluminum garnet There are also orange, green, blue, violet, purple, ultraviolet LEDs.

For more details on elements used for each color go here.

Above: 1958: Walter T. Matzen (top) and Bob Biard (bottom) worked on parametric amplifiers, this helped lay groundwork for the LED. Later Gary Pittman and Mr. Biard worked on varactor diodes which led to the LED as we know it. Read the full story of their work with this PDF here.

* 1972: Herbert P. Maruska & Jacques Pankove developed the violet LED which set the stage for development of a bright blue LED in 1993

Photos: Randy Lamb, UC Santa Barbara / Semicon West 2012 / PD-USGOV / Bob Biard

1907 - H.J. Round discovered electroluminescence when using silicon carbide and a cats whisker. Oleg Losev independently discovered the phenomena the same year. London, United Kingdom

1920s - Oleg V. Losev studied the phenomena of light emitting diodes in radio sets. His first work on 'LEDs' involved a report on light emission from SiC. In 1927 he published a detailed report but his work was not well known until the 1950s when his papers resurfaced. Saint Petersburg, Russia

1961 - James R. Biard. "Bob" Biard and Gary Pittman developed the Infrared LED at Texas instruments. This was the first modern LED. It was discovered by 'accident' while TI tried to make an X-band GaAs varactor diode. The discovery was made during a test of a tunnel diode using a zinc diffused area of a GaAs (Gallium Arsenide) semi-insulating substrate. Dallas, Texas Photo: Robert Biard

1961 - Gary Pittman worked together with James R. Biard. He had started working in 1958 with semiconductor GaAs for the creation of early solar cells. He discovered and developed the infrared LED with James R. Biard. Dallas, Texas

1962 - Nick Holonyack Jr. develops the red LED, the first LED of visible light. He used GaAsP (Gallium Arsenide Phosphide) on a GaAs substrate. General Electric. Syracuse, New York Photo: PD-USGOV

1972 - M. George Craford creates the first yellow LED at Monsanto using GaAsP. He also develops a brighter red LED. St. Louis, Missouri Photo: Semicon West 2012

1972 - Herbert Maruska and Jacques Pankove develop the violet LED using Mg-doped GaN films . The violet LED is the foundation for the true blue LED developed later. RCA Labs , New Jersey  

1979 - Shuji Nakamura develops the world's first bright blue LED using GaN (Gallium nitride). It wouldn't be until the 1990s that the blue LED would become low cost for commercial production. Tokushima, Japan Photo: Randy Lamb, UC Santa Barbara

1976 - Thomas P. Pearsall develops special high brightness LEDs for fiber optic use. This improves communications technology worldwide. Paris, France Photo: T.P. Pearsall

What is an OLED?

The Organic LED is made of a layer of organic electroluminescent material with p/n junction sandwiched between to electrodes. At least one of the electrodes is transparent so the photons can escape. Similar to an EL lamp , current is passed through a semiconductor (like the phosphor in an EL lamp), however the difference is that an OLED uses a p/n junction were there is a recombination of p and n carriers. EL (TDFEL, TFEL, powder EL) technology only uses a material excited by current to make light.

The semiconductor in an OLED is organic which means it contains carbon. The OLED uses one of two kinds of compounds: polymers or 'small molecule' . Read more about how it works below.

Uses: Lamps - short distance indoor lamps (produces a diffused light) Displays - small: phones and media devices and large: televisions, computer monitors

Advantages: -The units are lighter than traditional LEDs and can be made thinner as well -OLEDs can provide a more energy efficient alternative to LCD computer and television monitors -Can be used in a myriad of new applications in which lighting technology has never been used before

Disadvantages: -The cost of OLEDs is still high and each unit produces less lumens than a normal LED -The technology is still under development so the life of the OLED is being researched as new materials are used and tested each year. Until more research is done we will not know how these lamps with new materials compare with established technology.

Displays (computer monitors, televisions, mobile phone screens):

The OLED display is made by using multiple layer construction along with transistors which control whether each pixel is on or off. This is very similar to EL displays. The OLED display has the potential to be more efficient and thinner than the LCD. One advantage is that does not need a cold cathode fluorescent backlight like an LCD. The lack of a backlight means it can better display blacks (the back light always seeps through in black areas of the screen). The OLED display can also provide better contrast ratios than an LCD . The OLED display may also be made into a thin flexible material which could roll up like a newspaper. Currently the OLED is not as bright as EL or LCD displays it works better in areas with less ambient light. That may change as engineers work to increase luminosity.

Below: our simple video on OLED use in monitors and smart phones:

How the OLED Works:

Early OLEDs had one layer of organic material between two electrodes. Modern OLEDs are bi-layer, they have an emissive layer and conductive layer sandwiched between two electrodes (see diagram above).

1. Electric current passes from the cathode to the anode. It passes through two layers of organic molecules.

2. The first layer the electrons pass into what is called the emissive layer . Electrons leave the conductive layer making 'holes' (positive charge). Meanwhile in the emissive layer there are excessive electrons (negative). The 'holes' jump to the emissive layer along the border of the two layers where they recombine with electrons (this place is the p/n junction). When the electrons join the holes light is emitted.

Light color is dependent on the materials used in the organic or polymer layers

Types of OLEDs: LEC - Electrochemical Cell - this has ions added to the OLED PMOLED - Passive-matrix OLED - the first display technology, developed in the mid 90s AMOLED - Active-matrix OLED - used in displays, it has a switch built into it in the form of a thin film transistor backplane. The transistor allows the unit to be switched on and off. PLED - polymer LED Polymer LEDs use a plastic to emit light. They have the properties of semiconductors yet are versatile and low cost to produce. The layers that emit light are similar to an ink and will be very cheap to manufacture once stable compounds and processes are developed.

Deeper understanding of these improvements requires a basic background in chemistry and physics, you also can read more detail here .

The Future:

OLEDs will allow for thinner TV and computer displays, transparent "heads up" displays, flexible displays, flat roll-on surface lights on the sides of buildings or vehicles, changing camouflage displays for military vehicles, new photovoltaic applications, and much more. We can expect a lower production cost compared to LEDs due to less part assembly. At the moment OLEDs need more lab work to reach full potential.

Carbon nanotube technology is being developed for use with the OLED .

Timeline of major events: 1979 - Discovery of organic electroluminescent materials, Kodak 1987 - First organic light emitting diode built at Kodak 1990 - First PLEDs discovered, Cambridge University 1997 - First commercial PMOLED displays produced at Pioneer 1998 - First phosphorescent OLED developed 2007 - Samsung Mobile Display develops the first commercial AMOLED (active matrix organic LED) display.

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Lamps are presented in the order of chronological development

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The Electric Light

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Useful Links, More Resources: OLEDs: The PLED: Donal Bradley, Jeremy Burroughes and Richard Friend: Nature paper highlighted in: www.nature.com/physics/looking-back (This is the most highly cited paper in the field. DDCB was corresponding author.) Royal Society Bakerian Lecture: http://royalsociety.org/royalsociety.tv/?from=footer (Freely viewable on-line) Another RS video on plastic electronics: http://www.youtube.com/watch?v=0D_W_q1a0vU Centre for Plastic Electronics Homepage: http://www3.imperial.ac.uk/plasticelectronics DDCB Home page: http://www3.imperial.ac.uk/people/d.bradley LEDs: The First Practical LED by Thomas Okon and Bob Biard

Website, graphics and article by M. Whelan Thanks to assistance from Bob Biard, Chihaya Adachi, Chris King, Donal Bradley, Tetsuo Tsutsui and Ted Tohma

Sources/References: University of Rochester Wikipedia: LED, Electron Hole, YAK, OLEDs Edison Tech Center: Interview with Robert N. Hall Interview with John D. Harnden Jr. Also thanks to information provided by Jeremy Burroughes, Robert Biard oled-info.com businesswire.com/news cnx.org Donal Bradley US Patents: 67794676 Pakbaz Chihaya Adachi Contributions of Prof. Tetsuo Tsutsui in R&D of OLED technology H. Maruska James R. Biard Photos: Edison Tech Center Whelan Communications US Government Semicon West UC Santa Barbara T.P. Pearsall University of Rochester University of Michigan J. Robert Biard Steve Van Slyke Jeremy Burroughes Imperial College, London Ted Tohma Chihaya Adachi Tetsuo Tsutsui

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Potato Light Bulb Experiment

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(Physics for ages 8+)

If you’re looking for an exciting and boredom-busting activity, this just might be the one for you! Did you know you can use potatoes to light up a light bulb ? It seems crazy, but there is electrical energy all around us and even in everyday things like the food we eat. The video above shows exactly how it’s done. Here’s what you’ll need:

Potatoes Copper wire or copper nails Iron-galvanized nails Electrical wire (with or without alligator clips) Light bulb Voltmeter (optional) Adult supervision (Adult supervision at all times please)

• Start by inserting a 3-inch piece of copper wire about half-way into each of your potatoes (use 2, 3, or more potatoes if you’d really like to ramp up the voltage and brightness of the light bulb).
• Next, insert an iron-galvanized nail half-way into each of your potatoes. For best results, try to insert the nails about an inch away from the copper wire pieces.
• If you are using thin electric wire without alligator clips, you will need to remove some of the plastic covering. Cut two 6-inch strips of wire per potato you are using (if you are using 2 potatoes you need 4 strips, 3 potatoes will need 6 strips, and so on). Have an adult help you remove about ½ inch of plastic covering from both ends of each of the wire strips.
• You will need to attach the wires to your nails to complete an electrical circuit. In doing this, it is important to note the copper wire is the positive terminal (like the positive end of a battery), and the iron nail is the negative terminal. If you are using wires with alligator clips, simply clip one end to the copper wire of potato 1, and the other end to the iron nail of potato 2. If you are starting with just one potato, clip one wire from the copper wire to the light bulb, and connect another wire to the iron nail and light bulb. If you are using wires without alligator clips, simply wrap the exposed ends of the wire around the tops of the iron nails and copper wire pieces.
• Complete your circuit by attaching a strip of wire from the positive terminal (copper wire) of one potato to the negative terminal (iron nail) of the next potato. When you are finished, the light bulb should be attached to the negative terminal of the first potato and to the positive terminal of the last potato in the series. Please see the video for clarification on building this circuit.
• If you have voltmeter, replace the light bulb with the test terminals of the voltmeter to test the voltage coursing through the potato circuit. Try starting with a small circuit of just one potato and work your way up to several potatoes, testing the voltage of each circuit. You can also try different types of potatoes to see which kind makes the most powerful circuit (for example: Russet versus Yukon gold).

A potato is made up of water, sugar, and acid. When certain metals, like the copper and galvanized iron, are inserted into it, they react and create a flow of electrically charged molecules to move from the negative terminal to the positive terminal.

This reaction also released hydrogen gas as the charged molecules move through the entire potato circuit. Each potato releases a certain voltage, so connecting them in a series increases the total voltage output, which in turn brightens the light bulb. What other kinds of food might work to create a “ food battery ?”