Question

A real battery has an emf $ϵ$ and an internal resistancer. A variable resistor R is connected across the terminal of the battery. A current I is drawn from the battery and the potential difference across the terminal on the battery is V. If R is slowly decreased to zero, which of the following best describes I and V?

• A. I decreases to zero, V approaches
• B. I approaches an infinite value, V decreases to zero
• C. I approaches $ϵ/r$, V approaches
• D. I approaches $ϵ/r$, V decreases to zero

Answer 1

The correct option is D I approaches $ϵ/r$, V decreases to zero

$I=\frac{\epsilon }{r+R}$

$v=IR$

$\therefore$ when $R\to O$

$I\to \frac{\epsilon }{r}$

$v\to O$

Ans $D$