Two conductors are made of the same material and have the same length. They each have circular cross sectional areas. The ratio of their radii is 2:1. they carry the same current. What is the ratio of the electrical potential across their lengths?

Question

i know that you use R=P(L/A) when your trying to find the cross sectional area. But i don't know what to use when there radii is 2:1

Answer 1

The larger diameter wide has four times the cross sectional area of the thinner wire, and 1/4 of its resistance.

If they carry the same current I, the voltage drop V = IR is four times higher for the thinner wire.