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Physics Question on Current electricity

A potentiometer has uniform potential gradient. The specific resistance of the material of the potentiometer wire is 10−710^{-7} ohm metre and the current passing through it is 0.1 ampere. Cross-section of the wire is 10−8 m210^{-8}\,m^2. The potential gradient along the potentiometer wire is

A

10−8 Vm−110^{-8}\,Vm^{-1}

B

10−2 Vm−110^{-2}\,Vm^{-1}

C

10−6 Vm−110^{-6}\,Vm^{-1}

D

10−4 Vm−110^{-4}\,Vm^{-1}

Answer

10−2 Vm−110^{-2}\,Vm^{-1}

Explanation

Solution

R = ρlA=10−710−6l=110\rho \frac{l}{A} = \frac{10^{-7}}{10^{-6}} l = \frac{1}{10}
P.D. = I.R. = 0.1 ×110=1100 \times \frac{1}{10} = \frac{1}{100}
Potential gradient = Vl=1100=10−2 V/m\frac{V}{l} = \frac{1}{100} = 10^{-2} \, V/m