Energy
doesn't come just from burning gasoline, coal, or oil.
It can also come from food, or more specifically the
chemicals in food. In this activity, you will create
a chemical reaction with the acid of a lemon and metal
to create energy - enough to power a small light.
You
Will Need:
One
or more lemons. The more you have, the more energy
you will create.
Zinc
electrodes - a 3cm x 0.5cm piece of zinc metal, obtainable
at local hardware stores. Alternatively, you can
use a "galvanized" zinc-coated screw, nail, or penny
made after 1982. (One per lemon)
Copper
electrodes - similarly sized piece of copper metal.
Alternatively, you can use a penny that was made
before 1982. (One per lemon)
LED
lightbulb
Copper
wire – long enough to create a circuit from
the zinc electrode to the lightbulb to the copper
electrode. (One per lemon)
What
to Do:
Stick
the zinc electrode into the lemon. This is
now the negative electrode.
Stick
the copper electrode on the opposite side so that
it doesn’t touch the zinc electrode. This
is now the positive electrode.
Repeat
steps 1 & 2 for each lemon. Then connect the lemons
together positive to negative (zinc to copper) with
the copper wire.
Connect
the LED lightbulb to the two electrodes with copper
wire. The wire that sticks out of the flat
side of the lightbulb should be connected to the
negative side (zinc) of the chain of lemons and the
wire that sticks out of the round side should be
connected to the positive side (copper) of the chain
of lemons.
Check
it out!
What's the Science?
The
lemon battery is made up of two different metals, copper
and zinc. Electric current enters and
leaves the battery through these points. These "electrodes"
are placed in an "electrolyte,"
the acid from the lemon, which is a solution that
can conduct electricity.
A
chemical reaction takes place between the acid and metal
which causes electrons, which is what energy is made
of, to gather toward the negative end of the electrodes
and electrons to be lost on the positive side of the
electrodes. A
current flows from the negative to positive ends in
order to push out the excess electrons and for those
electrons to take the place of the electrons that were
lost on the positive end.
This
is enough energy to make the LED light to light up.
Using other metals and acidic fruits can have differences
in how well they create energy. Consider trying other methods
out!
Experiment
Demonstration
When you're visiting the California Science
Center, be sure to check out the Transportation exhibit
in Creative World to learn more about energy and fuel
sources.
