Question

A potentiometer wire has length 2 m and resistance 6 . The resistance that must be connected in series with the wire and an accumulator of 2 emf 4 v, so as to get a potential gradient 1 mv per cm on the wire is

Answer 1

Answer:

114

Explanation:

Length = 2m

Resistance = 6

Thus, with a potential gradient of 1 mV per cm, the net voltage across the potentiometer will be -

V = 1 mV/cm x 200 cm = 200 mV = 0.2 V

Since, accumulator voltage = 4 V,

The voltage will be divided among the potentiometer and the series resistance, thus voltage-

V = (6x4)/(6 + R) = 0.2

= 24/0.2 = 6 + R

= 6 + R = 120

= R = 114

Hence 114 ohm's of resistance needs to be connected in series to get a potential gradient of 1 mV per cm on the wire