Question

A battery has e.m.f. $4V$ and internal resistance $r$. When this battery is connected to an external resistance of $2\,\Omega$, a current of $1A$ flows in the circuit. How much current will flow if the terminals of the battery are connected directly

• A. 1A
• B. 2A
• C. 4A
• D. infinite

Answer 1

Answer: (B)

2A

Answer 2

I = $\frac{E}{R + r}$ or (R + r) = $\frac{E}{I} = \frac{4}{I}$ = 4 $\therefore$ r = 4 - R = 4 -2 = 2 $\Omega$ I = $\frac{E}{r} = \frac{4}{2}$ = 2 A