Question

A wire having the diameter of 1.2 mm and resistively of 100 * 10 ^ - 1 * Omega * m at 0°C is connected. across a cell of emf

1.5 V and gives a current of 10 mA. Calculate the length of the wire.

Answer 1

We know that

V=iR

$R=\frac{V}{I}$

$R=\frac{1.5}{0.01}=150\Omega$

We know that

$R=\frac{\rho l}{A}$

$l=\frac{RA}{\rho}$

$$l=\frac{150\times\pi\times 36\times10^{-8}}{10}=1.69\times10^{-5}m$$