Question

Two cell each of e.m.f 1.5 volts and internal resistance of 1.5 ohms are connected In series.What is the currents in the resistor of 20 ohms connected across the end of the series combination

Answer 1

for the two cells, e.m.f = $1.5\times2=3.0v$

Let the current flowing be I and the internal resistance be r.

$E=Ir+IR$

$3=2(1.5)I+20I$

$3=3I+20I$

$23I=3$

$I=0.13A$ (current through the 20 ohms resistor)