Battery Science Projects...
How Batteries Make Electricity
Before you do some battery science projects lets find out how they work.
Chemical reactions inside a battery create a large number of free electrons.
The flow of these electrons is the current that powers everything from
flashlights to cameras to toys.
Parts
of a battery
Cathode-the positive terminal
Anode- the negative terminal
Electrolyte- the chemicals in the battery that produce the free
electrons
Dry Cell Battery

The chemical reaction
between the electrolyte and the zinc cannister produces a surplus of electrons
at the anode. The cathode has far fewer electrons thus creating a potential
difference between the two electrodes. The electrons want to equalize this
difference by moving toward the lower build up at the cathode.
The electrolyte though
prevents the electrons from moving to the cathode. When a conducter such as a
wire is placed across the electrodes then the electrons can move to the
cathode. This flow is called electricity or electric current. This current flow
of electrons is what powers battery operated devices such as flashlights and
all types of electronics kits and devices.
When you start doing battery science projects it
will be important to know how batteries work and how to measure the electricity
they produce. By learning a few simple principles you will be prepared for some
really interesting science fair projects.
Measuring Electricity In Battery Science
Projects
Volts
We explained that the
difference in the amount of electrons at each electrode is what causes the
current of electricity to flow. But how do we measure how big that difference
is? We use a unit of measure called the volt to describe the potential
difference between the two masses of electrons. You will see this listed on all
batteries. A common flashlight battery is 1.5 volts. Voltage is the driving
force that makes the current flow
Amps
The next thing we need to
measure is the amount of current that flows through a conductor to a device.
This is the quanity of electrons that are moving through a wire or conductor of
electricity. This amount of current is measured in amperage. Also called amps
for short. For most of the battery science projects you will perform, the
current or amps will be small. The current flow depends on the device the batteries
are powering. Some pull a very small amount while others pull or use more. So
current will always be measured with a load connected to the battery. For a lot
of small batteries this will be measured in milliamps or thousandths of
an amp.
Watts
The power or amount of
work a battery is capable of doing is measured in watts. To get the
power we simply multiply the voltage times the amperage. The formula is P=I*V
where P is in watts, I is the current in amps, and V is the voltage in volts.
The power or watts is dependent on the device connected to the battery, just as
the current draw is. Some devices will pull a small amount of power and others
much more. But this is how power is measured for any particular device.
Ohms
All wires, conductors,
and elctrical devices have some resistance to the flow of electric current.
This resistance is measured in ohms or milliohms which is a
thousandth of an ohm. The resistance limits how much current can flow through a
device or conductor. Its one of the factors that determines how many watts a
device will pull. The lower the resistance the more amps and watts it will
pull. The higher the resistance the fewer amps and watts it will pull.
How To Make A Potato Battery
This experiment shows you
how to make a potato battery and measure the voltage it produces. The current
and the voltage produced will be small but it demonstrates how batteries work.
Potato Battery Experiment
Materials needed:
1.One large potato
2.A voltmeter to measure voltage
3.A glavanized nail. A four penny
or larger size will work
4.Two inch long piece of single
strand copper wire. Either 12 or 14 gauge
4.Piece of sandpaper or steel wool

Procedure:
a.Scuff the nail and copper wire with the sandpaper
or steel wool until its shiny
b.Push the nail and piece of wire
into the flat side of the potato about and inch keeping them an inch or more
apart. Make sure they don't touch.
c.Set the voltmeter on its lowest
whole number DC voltage. Its 2 on my meter.
d.Plug the red lead of the
voltmeter into the +voltage slot. Plug the black lead into the -negative
slot(also called common)
e.The nail will be the negative or
cathode of the potato battery and the copper wire will be the plus or anode
of the battery
f.Turn on the voltmeter and touch
the red positive lead to the copper wire and the black negative lead to the
nail
My potato battery
produced 0.88 volts. The current from this battery will be too small to light
a bulb or power an appliance.
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