current-electricity Question 56

Question: Q. 10. A potentiometer wire of length 1 m has a resistance 10Ω. It is connected to 6 V battery in series with a resistance of 5Ω. Determine the emf of the primary cell which gives a balance point at 40 cm.

A [Delhi I, II, III 2014]

Show Answer

Solution:

Ans. Current flowing in potentiometer wire,

I=VR+R

where, R is the resistance of potentiometer wire and R=5Ω

I=610+5 A=0.4 A1/2

Potential drop across the potentiometer wire

V=IR =0.4×10 V=4.0 V1/2

Potential gradient k=V/l=4.0 V/m1/2

Unknown emf of the cell (E)=kl1/2

=4.0×0.4 V =1.6 V

[CBSE Marking Scheme, 2014]



Table of Contents

NCERT Chapter Video Solution

Dual Pane