Download Potato Battery

Building a Potato Battery
Where does energy come from?
Energy is all around us! We have electricity, sunlight, food, and many more types of
energy. Energy can come in many different forms and we can change energy from one type to
another. For example, energy from the sun in the form of light energy, can be converted into
electricity by using solar panels. The energy you use to run on a treadmill comes from the
energy stored in food we eat. Our bodies take the energy in food and converts it to energy we
can use when running. Today we will be turning chemical energy from food into light!
Some types of energy
Light/Sunlight
Electrical
Chemical (food)
Heat
For this experiment, we will be taking a simple potato and using it as a battery to light
up a light bulb! The chemical energy from the potato will be turned into light energy. Potatoes
contain a chemical that is an electrolyte. An electrolyte is a solution that contains charged
molecules called ions. The simplest electrolyte is salt water. You also may have heard about
electrolytes in drinks like Gatorade and Powerade. All this means is that they have salt in them!
The electrolyte in potatoes allows electrons to flow between electrodes (zinc and copper metal)
which conduct the electricity. The picture below shows how electrons flow to make electricity.
Electron flow
Copper
Metal
Zinc
Metal
Electrolyte
(helps electrons flow)
To test if a potato contains enough electrolyte to help electrons flow, we will be testing
the electricity produced between the copper and the zinc metal. Once we determine how much
electricity there is in a potato, we will then try to light a lightbulb with our potato! Follow the
steps below very carefully after answering the following questions:
Prelab Questions:
1. What kind of energy does a potato have?
2. What is in the potato to help the electrons flow to create electricity?
3. What are we using as electrodes in our potato battery?
Procedure:
Materials:
1 Potato
Voltmeter
2 Zinc plated nails
Alligator clips
2 Pennies
Plastic Knife
2 Pieces of copper wire
LED light
Directions:
1. Cut the potato in half
2. Insert a nail into each half of the potato
3. Using the green pad, scrub the pennies so they are shiny.
4. Cut a small slit away from the nail in each potato and insert the penny
5. Turn the dial on the voltmeter to the 20 setting on the DCV (left) side
6. Touch the black wire from the voltmeter to the nail and the red wire to the penny. Do
this for each half and record the voltage in the table below
Voltage
Half #1
Half #2
Total Voltage (add half #1 and half #2)
7. Using the greed pad, scrub the pieces of copper wire to remove any oxidation.
8. Take out the penny from each potato (leave the nail in) and wrap the copper wire
around your finger to form a coil. Insert one coil into each potato where the penny was.
9. Repeat step 5 to measure the voltage with the copper wire instead of the copper penny.
Record your results
Voltage
Half #1
Half #2
Total Voltage (add half #1 and half #2)
Questions:
1. If a lightbulb needs 2.5 Volts to light up, will the two potato halves with the pennies
have enough electricity to light the bulb?
2. Will the 2 potatoes with the copper wire have enough electricity to light up the
lightbulb?
3. Why do you think the copper wire produces more electricity than the penny?
4. If your potato halves don’t have enough electricity to light the lightbulb, what could you
do to increase the amount of electricity produced?
Procedure to light up the LED bulb:
1. Connect the nail from one potato to the copper coil from the other
2. Connect the free copper wire to the red wire from the voltmeter and the nail to the
black wire. Record the voltage.
3. Replace the voltmeter with the lightbulb to check if your potatoes can light the
lightbulb! Make sure to connect the nail to the short wire on the light and the copper
coil to the long wire.
*If the light doesn’t light up, you will need to combine more potatoes!
Questions:
1. How much voltage did the potatoes read when putting both halves together? Was this
more or less then when you added the individual voltages in the table?
2. Did the potatoes have enough electricity to light the LED bulb? Why or why not?