Question

THE STORAGE BATTERY OF A CAR HAS AN EMF OF 10V,IF INTERNAL RESISTANCE IS 0.2OHM.WHAT IS THE MAXIMUM CURRENT DRAWN FROM THE BATTERY

Answer 1

emf of car battery is 12V and internal and resistance of the battery is 0.4 ohm .

so, the maximum current will be obtained when no external resistance is offered by with joining the two terminals.

I mean, R_{ext}=0R

ext

=0

see daigram,

according to Kirchoff's law,

E - r × I - Rext × I = 0 ,

here I is the maximum current passing through battery.

I = E/(Rext + r)

= 12/(0 + 0.4) = 30A

hence maximum current = 30A