Question

plz answer as soon as possible

Answer 1

$resistance \: is \: given \: as \: R = \frac{\rho l}{a}$

if we keep the material same, resistivity will remain same

we are keeping the length same.

diameter is increased to 3 times. So area will change.

$A= \frac{\pi {d}^{2} }{4}$

Area is proportional to d^2. So if d changes to 3d, area A will become 9A

New resistance will be

$new \: resistance,\ R' = \rho \frac{l}{9a} = \frac{R}{9}$

So new resistance will decrease to R/9.

Answer 2

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$resistance \: is \: given \: as \: R = \frac{\rho l}{a}$

if we keep the material same, resistivity will remain same

we are keeping the length same.

diameter is increased to 3 times. So area will change.

$A= \frac{\pi {d}^{2} }{4}$

Area is proportional to d^2. So if d changes to 3d, area A will become 9A

New resistance will be

$new \: resistance,\ R' = \rho \frac{l}{9a} = \frac{R}{9}$

So new resistance will decrease to R/9.

HOPE SO IT WILL HELP.....