Three cells each of e.m.f 1.5 V and internal resistance 2.5Ω are connected as shown in the diagram above. Find the net e.m.f and the internal resistance
A. 1.5V, 7.50Ω
B. 1,5V, 0.83Ω
C. 4.5V, 7.50Ω
D. 4.5V, 0.83Ω
Correct Answer: B
Explanation
Since the cells are connected in parallel the net e.m.f is that of one cell, E.
However the effective internal resistance should be added as parallel resistance.
=> 1/v + 1/25 + 1/25 + 1/25 = 1.2
∴ v = 0.83Ω
∴ Effective e.m.f and internal resistance are respectively = 1.5V and 0.83Ω
