Question

The maximum current power in the external battery circuit at a current of 0.2A is 4W.find the emf and the resistance of the battery

Answer 1

Maximum power given $(P) =4W$

Current at Maximum power $(I) =0.2A$

The load resistance $(R) =\frac{P}{I^2}=\frac{4}{0.2^2}=100\varOmega$

According to maximum power transfer theorm, during maximum power transfer load resistance =source resistance

i.e Source resistance$(Rs) =100\varOmega$

Emf of battery$(E) =I(R+Rs) =0.2\times200=40V$