The storage battery of a car has an emf of 12v .If the internal resistance of battery is 0.4ohm.what is the maximum current that can be drawn from the battery?

To find the maximum current that can be drawn from the battery, we use Ohm’s law and the concept of internal resistance.

Given data:
Electromotive force (emf), E = 12 V
Internal resistance of the battery, r = 0.4 Ω
Maximum current occurs when the external resistance R = 0 (short circuit condition).
Formula:
The total resistance in the circuit is given by:

R_total = r + R

For maximum current, set R = 0, so:

R_total = r = 0.4 Ω

Using Ohm’s law:

I = V / R

Substituting the values:

I = 12 V / 0.4 Ω
I = 30 A

Final Answer:
The maximum current that can be drawn from the battery is 30 A.