Two identical batteries each of e.m.f 2 V and internal resistance $1 \Omega$ are available to produc

Question

Two identical batteries each of e.m.f 2 V and internal resistance $1 \Omega$ are available to produce heat in an external resistance by passing a current through it. The maximum power that can be developed across $R$ using these batteries is\

Professor PC Thomas Classes · Answer

(b) : For maximum current, the two batteries should be connected in series. The current will be maximum when external resistance is equal to the total internal resistance of cells $i$. .e. $2 \Omega$. Hence power developed across the resistance $R$ will be $$ I^{2} R=\left(\frac{2 E}{R+2 r}ight)^{2} R=\left(\frac{2 	imes 2}{2+2}ight)^{2} 	imes 2=2 \mathrm{~W} $$