Question

A car battery of emf 12 V and internal resistance 5×10^-2 Ω, receives a current of 60 amp, from external source, then potential difference of battery is.

(a) 12 V 

(b) 9 V

(c) 15 V

(d) 20 V

Answer 1

(c) 15V 

When cell is changed by an external source, terminal voltage, V = E + Ir 

V = 12 + 60 × 5 × 10^-2

=15.