Three similar cells each of e.m.f 2V and internal resistance 2Ω are connected in parallel; the total e.m.f and total internal resistance are respectively?

A. 6V, 6.0Ω
B. 2V, 0.7Ω
C. 2V, 6.0Ω
D. 6V, 0.7Ω

Correct Answer:

Option B – 2V, 0.7Ω

Explanation

Total energy in parred connection is equal to emt of one cell, = 2v but total internal resistance is given by
(1)/r = (1)/r1 + (1)/r2 + (1)/r3 = (1)/2 + (1)/2 + (1)/2 = (3)/2
∴ r = (2)/3 = 0.67Ω