Graph

Plot a graph of resistance, R, in Ω on the y-axis against length, l, in cm on the x-axis). Draw the line of best fit.

A graph of resistance, R, in Ω on the y-axis against length, l, in cm on the x-axis).

Conclusion

We can see from the graph that as the length of the wire, l, increases, the resistance, R, also increases.

This agrees with our prediction.

In fact, since the line of best fit is a straight line through the origin, we can be even more precise.

We can say that, for a metal wire at constant temperature, the resistance is directly proportional to the length of the wire.

If you double the length of the wire you double its resistance.