A potentiometer wire , 4 m long and having a resistance of 10 `Omega`, is connected in series with an external resistance of `38 Omega` and a cell , of emf 2 V and internal resistance `2 Omega`. Calculate the potential gradient along the wire.

Explanation

Date : ` L = 4 m , r = 10 Omega, E = 2 V, r_(C) = 2 Omega, R = 39 Omega`
The potential difference across the wire is
`V = Ir = (E/(r + r_(c) + R))r`
` :. ` The potential gradient along the wire is
` V/L = (Er)/((r + r_(c )+R)L) `
` =(2 xx 10)/((10 + 2 + 38) xx4) `
` = (20)/(50 xx 4) = 20/200 = 0.1` V/m