Four cells each of e.m.f 1.5V and internal resistance of 4Ω are connected in parallel. What is the effective e.m.f. and internal resistance of the combination?
- 6.0V, 16Ω
- 6.0V, 1Ω
- 1.5V, 4Ω
-
1.5V, 1Ω
The correct answer is: D
Explanation
Since all the cells are connected in parallel, the effective e.m.f. is just that of one single cell. Which means e.m.f. = 1.5V
However, the effective internal resistance adds as parallel arrangement given as
1/r = 1/r1 + 1/r2 + 1/r3 + 1/r4
= 1/4 + 1/4 + 1/4 + 1/4
= 1Ω
∴ r = 1Ω
Answer = 1.5V, 1Ω