Q: A cell of e.m.f 2 volt and internal resistance 1.5 Ω is connected to the ends of 1 m long wire. The resistance of wire is 0.5 Ω /m. Find the value of potential gradient on the wire.
Sol: $\large k = \frac{I R}{L} = ( \frac{E}{R+r} ) \frac{R}{L}$
$\large k = ( \frac{2}{0.5 + 1.5} ) \times 0.5 $
k = 0.5 V/m