A cell of emf and internal resistance is connected to an external resistor

PHYSICS · Single correct · A Level · Physics · Electricity · Electricity

Problem

A cell of emf

\mathcal{E}

and internal resistance

r

is connected to an external resistor

R

. Which of the following expressions gives the magnitude of the steady current in the circuit? (a)

I = \dfrac{\mathcal{E}}{R-r}

(b)

I = \dfrac{\mathcal{E}}{R}

(c)

I = \dfrac{\mathcal{E}}{R+r}

(d)

I = \dfrac{R}{\mathcal{E}+r}