Question

What will be the resistance of a conductor if its length is increased by 3 times and area of cross section becomes half . also find the specific resistance of the conductor.

Answer 1

we know that resistance is given as

R = ρL/A

so,

R ~ L

and

R ~ 1/A

so

R ~ L/A

the new resistance will be

R' ~ L'/A'

here,

L' = 3L

and

A' = A/2

so,

R' ~ 3L/(A/2)

~ 6(L/A)

thus,

R' ~ 6R

the resistance will increase six times its initial value.