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

(d) `V = xl implies iR = xl`
`implies ixx 10 = ((2 xx 10^(-3))/(10^(-2))) xx 50 xx 10^(-2) = 0.1`
`implies i= 10 xx 10^(-3) A = 10 mA`.