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Science Projects > Physics & Engineering Projects > How To Make a Light Bulb  

How To Make a Light Bulb

Adult supervision recommended.

What You Need:

• Pint glass canning jar with lid
• 3 feet insulated copper wire
• 6-volt battery
• Thin iron wire (unraveled picture hanging wire works great)

What You Do:

1. Cut the copper wire in half and strip at least one inch of insulation off the ends of each length of wire. Next, punch two holes in the jar lid. (You can use a nail for this.) Thread one end of the wire through each hole in the lid.

2. Make a hook at the end of each wire (the end that will be inside the jar when you put the lid on). Twist two or three strands of the iron wire together, then twist the ends around the hooks in the copper wire. The iron wire will act as your filament.

3. Place the lid (with the filament and wires attached) in the jar and carefully connect the free ends of the copper wire to the terminals on the 6-volt battery. Once both ends are connected to the battery, the current should start flowing, causing the filament to heat up and give off a bright orange glow.

Your homemade light bulb is working! The light will last for anywhere from a few seconds to a few minutes, depending on your filament. (Note: once your filament is burned out, don’t touch it right away – it will be very hot.)

• You might also be interested in our Make a Pinhole Camera and Make a Vacuum Cleaner projects.

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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:

Top 15 Light Related Science Experiments

Light experiments lets us unlock some of nature’s most intriguing riddles and appreciate the magic that illuminates our everyday experiences.

We have carefully selected the best light-related experiments, prioritizing fun and educational experiences that will surely engage young minds.

Our compilation of light experiments will illuminate the minds of students and teachers alike. This curated collection offers an extraordinary opportunity to explore the captivating world of light through hands-on activities.

1. Potato Light Bulb

Prepare to be amazed by the power of potatoes in our extraordinary potato light bulb experiments! In these captivating experiments, students will discover the remarkable ability of a humble potato to generate electricity and light up an LED bulb.

Learn more: Potato Light Bulb

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4. Newton’s Light Spectrum Experiment

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5. Newton’s Prism Experiment

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9. Home-made Kaleidescope

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Learn more: Home-made Kaleidescope

10. Push Things with Light

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12. Exploring Shapes and Patterns on a Mirror Box

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Learn more: Exploring Shapes and Patterns on a Mirror Box

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Learn more: Light Patterns in a Box

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Potato Light Bulb Experiment

(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 ?”

• Electronics

Potato Light Bulb Experiment For Kids

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.

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

Cite This Article

Stevens, James. "Potato Light Bulb Experiment For Kids" sciencing.com , https://www.sciencing.com/potato-light-bulb-experiment-kids-12105514/. 13 March 2018.

Stevens, James. (2018, March 13). Potato Light Bulb Experiment For Kids. sciencing.com . Retrieved from https://www.sciencing.com/potato-light-bulb-experiment-kids-12105514/

Stevens, James. Potato Light Bulb Experiment For Kids last modified March 24, 2022. https://www.sciencing.com/potato-light-bulb-experiment-kids-12105514/

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