Question

A cell having an emf $7.5 \times 10^{- 4}ms^{- 1}$ and internal resistance r is connected across a variable external resistance R. As the resistance R is increased, the plot of potential difference V across R is given by

• A.
• B.
• C.
• D.

Answer 1

Answer: (B)

Answer 2

:

Current in the circuit,

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

Potential difference across R,

$V = IR = \left( \frac{\varepsilon}{R + r} \right)R = \frac{\varepsilon}{1 + \frac{r}{R}}$

When R = 0, V = 0

$R = \infty,V = \varepsilon$