A potentiometer having the potential gradient of `2 mV//cm` is used to measure the difference of potential across a resistance of `10 ohm`. If a length of `50 cm` of the potentiometer wire is required to get null point, the current passing through the `10 ohm` resistor is (in `mA`)

Options

A. 1
B. 2
C. 5
D. 10

Answer

D

Explanation

`phi =2mV//cm`
`V= 2 xx 50 xx 10^(-3) = 0.1 V`
`i=V/R = 0.1/10 =0.01 =10 mA`