1. Electricity
Ohm's Law

2. The test Circuit This Circuit is called a test circuit.
We can put components in the gap to study or test them.
You are going to repeat Ohms experiment.

3. You change the voltage with the dial on the power pack!!
Rheostat set to high resistance
Voltage (v)
Current (A) 2 4 6 8
Rheostat set to medium resistance
Voltage (V
Current (A) 2 4 6 8
You change the voltage with the dial on the power pack!!
Leave the third column blank for now

4. using these axes, you can put the high resistance and
Medium Resistance. A small voltage gives a big current
Current
(Amps)
Now draw a graph
using these axes, you can
put the high resistance and
medium resistance
Results on the same axes
High Resistance. A big voltage gives a small current
Voltage (Volts)

5. How does the resistance affect The gradient of the graph?
The steeper the gradient the
Lower the resistance

6. Match up the resistances
with the pictures…
Medium A
High B
Low C

7. This is Georg Ohm, he discovered a relationship between voltage and current.
Today you are going to follow in his footsteps!

8. Voltage = Current x Resistance
V = I x R
Ohms Law
Voltage = Current x Resistance
Resistance is measured in Ohms, we use the Greek letter omega for this:

9. now fill in the third column of these tables.
Rheostat set to high resistance
Voltage (v)
Current (A)
Resistance (Ω) 2 4 6 8
now fill in the third column of these tables.
Use a calculator to help you
Rheostat set to medium resistance
Voltage (V
Current (A)
Resistance (Ω) 2 4 6 8

10. Challenge: - Can you relate Ohms Law to Y=mX, the equation for a line you learned in Maths?
Prepare an explanation for the rest of the class?