What causes or reduces resistance in a material?
Resistance can be thought of as the amount of distruption to the flow of electrons. If we look at the equation for resitivity:R=kl/A,where k is the resistivity of the material (and is dependant on the material), l is the length of the material and A the area. We can see that as l increases in size so does R. While if we increase the size of A, R will get smaller. Your answer is shown in the algebra for you, the reason for this is that as the electrons flow through a material, the further they have to flow the more likely they are to be interruped. Wheras if the material has a larger area they can flow more freely with less chance of collision.
DG
Related Physics A Level answers
All answers ▸Why does an α particle cause more ionisation than a β particle if they have the same kinetic energy?
Explain, in terms of the behaviour of molecules, how a gas exerts a pressure on the walls of its container. (4)
A gold leaf electroscope with a zinc plate top is charged by briefly connecting it to the negative electrode of a high-voltage supply. Explain how the gold leaf will appear and how the leaf can be caused to drop again.
Why does a skydiver go through two different terminal velocities?