Question

A piece of wire of resistance R is cut into three equal parts. These parts are thenconnected in parallel. If the equivalent resistance of this combination is R′, then theratio R/R′ is –


please help me ​

Answer 1

Explanation:

Let length of wire be= l

now

$r = \frac{ρl}{a}$

if the wire is cutted in three equal parts then

Rnew for each cutted wire is =R/3

now if they are connected in parallel

R'=

$\frac{1}{R'} = \frac{1}{ \frac{R}{3} } + \frac{1}{ \frac{R}{3} } + \frac{1}{ \frac{R}{3} } \\ = \frac{3}{R} + \frac{3}{R} + \frac{3}{R} \\ = \frac{3}{3R} \\ \frac{1}{R'} = \frac{1}{R} \\ so \: \frac{R}{R'} = 1$