Question

A battery of e.m.f. $E$ has an internal resistance $'r'$. A variable resistance $R$ is connected to the terminals of the battery. A current $I$ is drawn from the battery. $V$ is the terminal $P.D.$ If $R$ alone is gradually reduced to zero, which of the following best describes $I$ and $V$?

• A. $I$ approaches $E /r, V$ approaches $E$
• B. $I$ approaches infinity, $V$ approaches $E$
• C. $I$ approaches zero, $V$ approaches $E$
• D. $I$ approaches $E /r, V$ approaches zero

Answer 1

Answer: (D)

Current, $i=\frac{E}{R+r}$ when $R$ decreases to $0, i=\frac{E}{r}$
Similarly, potential difference $V=i R$ when $R$ decreases to $0, V=0$