4. Materials
• Rocks:
Iron pyrite, ore, white geode,
purple geode, peacock rock,
tiger eye, agate
• Tester:
Tape, wires, bulb, D cell
• Example conductors:
Tin foil, coins
5. How the tester works
You can’t see it, but the bulb is touching one terminal of
the battery and a wire is touching the other. The other
wire is touching the side terminal of the bulb. When you
touch both wires to a conductor, the bulb will light up,
because it will be a complete circuit.
6. Setup
Here we have proof that the tin foil and coins are
conductors. We touched one wire to the tin foil and
the other to the top of the coins. The bulb lit up,
meaning these are conductors.
7. Prediction
I was thinking that the iron pyrite would be a
conductor because it has “iron” in its name.
I thought that none of the other rocks would be
conductors.
8. Measured and controlled variables
Controlled variables:
We used the same wires,
D cell, tape, and bulb.
Measured variable:
We changed the type of
rock.
9. Observations
I did three trials for
each rock and I
observed that the
peacock rock and the
iron pyrite both lit
up.
10. Answer
My prediction was partly right and partly
wrong. The iron pyrite did light up, but the
peacock rock lit up too.
11. New questions ... and answers
Why did the peacock rock light up? Is it
because it has some type of metal in it?
Internet research: Peacock rock is almost completely
metal. It has a lot of copper and iron in it.
