JEE Main · 2019 · 11 Jan 2019 · Shift 2 · Current Electricity

In the circuit shown, the potential difference between

A

and

B

is:

Answer: (B)

Solution

The section between A and B carries the three cells in parallel across CD, so its voltage is the combined e.m.f. of cells in parallel,

V = \frac{E _{1} / r _{1} + E _{2} / r _{2} + E _{3} / r _{3}}{1/ r _{1} + 1/ r _{2} + 1/ r _{3}}

. With equal internal resistances and e.m.f.s of

1

2

V and

3

V, this reduces to the average

\frac{1 + 2 + 3}{3} = 2

JEE Main · 2019 · 11 Jan 2019 · Shift 2 · Single correct option