Question

Under what circumstances can the terminal potential difference of a battery exceed its emf?

Answer 1

Step 1: Given and diagram

Let the battery is charging,

Let $\epsilon$, r and i are e.m.f, internal resistance and current respectively.

Step 2: Formula used

$\Delta V=I\times r$

Step 3: Finding emf of battery

By applying Kirchhoff's law,

$V_A$ -$\epsilon$ -i*r=$V_B$

$V_A$ -$V_B$ =$\epsilon$ +ir

$\Delta V$ =$\epsilon$ +ir

$\Delta V$ >$\epsilon$

Hence, the terminal potential difference of the battery exceeds the e.m.f. during charging of the battery.