Question

A cylind of length l and uniform area of crosssection A has resistance R.Another conductor of length 2l and resistance R of the same material has area of cross section
(a)A/2
(b)3A/2
(c)2A
(d)3A
I need to know how to do it

Answer 1

Answer:

the answer is 2A

l' = 2l

R' = ρl'/A'

A' = ρl'/R'

A' = 2 ( ρl/R )

A' = 2A

the length of the conductor is doubled (2L) and so the resistance will be 2R. For the resistance to remain the same as R, the area of cross section is also doubled as 2A.

Hence, the area of cross section is 2A.