A storage battery of a car has an emf of 12 V. If the internal resistance of the battery is $0.4 \Om

Question

A storage battery of a car has an emf of 12 V. If the internal resistance of the battery is $0.4 \Omega$, what is the maximum current that can be drawn from the battery?

Professor PC Thomas Classes · Answer

The maximum current is drawn when external resistance is zero. $I_{max} = \epsilon / r = 12 / 0.4 = 30 A$.