Question

18. A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main
battery, used across the potentiometer wire, has an
emf of 2.0 V and a negligible internal resistance.
The potentiometer wire itself is 4 m long. When the resistance, R, connected across the given cell,
has values of (i) Infinity, (ii) 9.5 2, the 'balancing lengths', on the potentiometer wire are found to be
3 m and 2.85 m, respectively. The value of internal resistance of the cell is

(1) 0.25 2
(2) 0.95 2
(3) 0.5 2
(4) 0.75​

Answer 1

Answer:

(3)

Explanation:

Internal resistance of the unknown cell is

(

l

2

l

1

−1)R=(

2.85

3

−1)(9.5Ω)=0.5Ω

Answer 2

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