Aluminum and copper wires of equal length are found to have the same resistance. what is the ratio of their radii?

aluminum-copper

#1

aluminum and copper wires of equal length are found to have the same resistance. what is the ratio of their radii?

Answer:

the resistance is directly proportional to the length and resistivity
and inversely proportional to the cross sectional area (the square of the radius)

(Cu radius)² / (Cu resis) = (Al radius)² / (Al resis)

1.6 / (cr)² = 2.7 / (ar)²

1.6 / 2.7 = (cr / ar)²