Resistance of a Wire

Task

To investigate how the resistance of a wire is affected by the length of the wire.

Theory

What is resistance?

Resistance is a force which opposes the flow of an electric current around a circuit so that energy is required to push the charged particles around the circuit. The circuit itself can resist the flow of particles if the wires are either very thin or very long.

e.g. The filament across an electric light bulb.

How is it measured?

The resistance of a length of wire is calculated by measuring the current present in the circuit (in series) and the voltage across the wire (in parallel). These measurements are then applied to this formula:

Gradient = resistance

V = I x R

The other ways of writing Ohm's Law are:

R = V/I or I = V/R

Ohm’s Law

It is also relevant