Question

Two concentric circular loops of radii b and 2b, made of the same type of wire, lie in the plane of the page, as shown above. The total resistance of the wire loop of radius b is R. What is the resistance of the wire loop of radius 2b?

(A) R/4 

(B) R/2 

(C) R 

(D) 2R 

(E) 4R

Answer 1

The correct option is: (D) 2R 

Explanation:

The larger loop, with twice the radius, has twice the circumference (length) and R = ρL/A.