Question

Potentiometer wire,PQ of 1m length is connected to a standard cell E1. Anoyher cell, E2 of emf 1.02 V is connectes as shown in the circuit diagram with a resistance r and switch s. when swutch s open, null point is obtained at a distance of 51 cm from P. calculate a) emf of cell E1 . b) potential gradient of the potenstiometer wire and c) when switch s is closed, will null point move towards P or towards Q? give reasom for you answer

Answer 1

Answer:

(a) e.m.f across cell E1 is given as;

E1/ E2= l1/ l2

E1 = (l1/ l2)* E2 = (100/51)* 1.02 = 2 volts

e.m.f across cell E1 = 2 volts

(b) Assume that Electromotive force e.m.f of 1.02 volts is at separation of 51 centimeters so at the 100 centimeters it will become;

= (100/51)*1.02 = 2 volts

So the potential gradient will be;

Potential grad = 2*V/m

(c) Hence no current is flowing, so there will be no change because of the balance condition.