The resistance of a conductor of diameter d and length l is R Ω. If the diameter of the conductor is halved and its length is doubled, the resistance will be

(A) 2R Ω (X)
(B)  8R Ω ()
(C)  R Ω (X)
(D) 4R Ω (X)

Answers: The resistance of a conductor of diameter d and length l is R Ω. If the diameter of the conductor is halved and its length is doubled, the resistance will be 8R Ω.