GCSE Physics

Voltage & Current Graph: filament lamp

You can show that the resistance has changed by reading values of current and voltage from the graph.

Remember that we can calculate resistance (R) by using R = V÷I.

current-voltage graph for a filament lamp

What is the resistance when V=1 and V=3?

Read off values:
V=1, I=0.2
R = V÷I = 1÷0.2 = 5 ohm

V=3, I=0.4
R = V÷I = 3÷0.4 = 7.5 ohm

The resistance increases!

It's probably wise that you know how to do this!

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