A wire of length L and radius r has a resistance R. What is the resistance of a second wire made from the same material that has a length L/2 and a radius r/2?
(A) 4R
(B) 2R
(C) R
(D) R/2
(E) R/4
The correct option is: (B) 2R
Explanation:
R = ρL/A. If L ÷ 2, R ÷ 2 and is r ÷ 2 then A ÷ 4 and R × 4 making the net effect R ÷ 2 × 4
