Question

if the length of the conductor is doubled without changing its area, then the value of resistance becomes

please prove this for me

Answer 1

as resistance R = (rho) l/a
if Length l is doubled keeping area of x-section uniform then resistance will surely get doubled as R(new) = (rho) 2l/a
= 2 (rho)l/a
= 2 R
Hope it helps and if yes please mark as brainliest.

Answer 2

lets say length is L and cros section is A = pi * r ^2

Resistance, R = (roh * L)/ (pi * r^2)

 

if the length and cross section both are doubled then the resistance is

R2 = (roh *2L)/ (pi*4r^2)

Now R2/R = [(roh *2L)/ (pi*4r^2)] / [(roh * L)/ (pi * r^2)]

then R2 = R /2

 so, the resistance will be half of previous.