Question

In a potentiometer experiment when three cells A, B, C are connected in series the balancing length is found to be 740 cm. If A and B are connected in series, the balancing length is 440 cm and when B and C are connected in series, it is 540 cm. The e.m.f. of A, B, and C cells E_A, E_B, E_C are respectively (in volt) ______

विकल्प

• 1.5, 2.5, 3.5

• 1.5, 2, 3

• 1, 1.2, 1.5

• 1, 2, 3

Answer 1

In a potentiometer experiment when three cells A, B, C are connected in series the balancing length is found to be 740 cm. If A and B are connected in series, the balancing length is 440 cm and when B and C are connected in series, it is 540 cm. The e.m.f. of A, B, and C cells E_A, E_B, E_C are respectively (in volt) 1, 1.2, 1.5.

Explanation:

E_A + E_B + E_C = 740K ..................(1)

E_A + E_B = 440k ..................(2)

E_B + E_C = 540k .........................(3)

k = constant of proportionality

(1) + (2)

k440 + E_C = 740k

∴ E_C = 300k

E_B = 540k - 300k = 240k

E_A = 740k - 540k = 200k

If E_A = 1 V, E_B = 1.2 V, E_C = 1.5 V