Physics (AS & A Level) · May / June 2022 · Paper 13 · Question 35

A piece of conducting putty (modelling clay) of constant resistivity is formed into a cylindrical shape. The resistance R between its flat ends (shaded) is measured. The same volume of putty is re-formed into cylinders of different lengths L, and the resistance R between the flat ends is measured for each value of L. Which graph best shows the variation of R with L?

1. AGraph A: R constant, horizontal line
2. BGraph B: R proportional to L, straight line through origin
3. CGraph C: R increases with L, curve with decreasing gradient
4. DGraph D: R increases with L, curve with increasing gradient

As printed in the paper