Datasheet-1
Project 10
Materials Tester
If you have the build-your-own electromagnet connected to
the two-Spring socket (?1), disconnect its wires for this proj-
ect. Build the circuit and set the meter (M5) to the 1A setting.
Turn on the slide switch (S1) and touch (or connect) various
materials between the springs on the two--spring socket
See which materials are good at transporting electricity by
watching the meter current and lamp (L4) brightness. Try
string, the electrodes, a shirt, plastic, paper, two of your fin-
gers, wood, or anything in your home.
If the meter reads zero, switch it to the 1mA setting to see if
there is just a very small current. To help protect the meter,
always switch back to the 1A scale before testing a new cir-
cuit.
1A
Which materials gave the highest reading on the meter, and
which gave the lowest?
Some materials, such as metals, have very low resistance to electricity will
make the lamp bright and give a large current measurement on the meter.
These materials are called conductors. Conductors have electrons that are
loosely held to the nucleus and can move easily.
Other materials, such as paper, air, and plastic, have very high resistance to
electricity. These will turn off the lamp and give a zero current measurement
on the meter even in the 1mA setting. These materials are called insulators.
Insulators have their electrons locked in tight and have no room for more.
The best conductor ever discovered is silver, which is very expensive. Cop-
per is the second best conductor, and it is used in almost all electrical wires.
You can use Ohm’s Law to measure the resistance of the materials you
tested. The voltage is about 4.5V, and use the current measured on the meter.
Voltage
Current
Resistance =
What is Resistance? Take your hands and rub
them together very fast. Your hands should feel
warm. The friction between your hands con-
verts your effort into heat. Resistance is the
electrical friction between an electric current and
the material it is flowing through; it is the loss of
energy from electrons as they move through the
material.
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