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 mA
B. 2 mA
C. 5 mA
D. 10 mA

Answer

D

Explanation

P.D. across the resistance = IR
P.D. across 50 cm length of the potentiometer wire
`=50 cm xx(2m V)/(cm)=100 m V = 0.1V`
`therefore I= (V)/(R )=(0.1)/(10)=(1)/(100)A=10 mA`