Current Electricity Ques 102
102. 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
(a) $3.2 W$
(b) $2.0\ \text{W}$
(c) $1.28 W$
(d) $\frac{8}{9} W$
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Answer:
Correct Answer: 102.(b)
Solution:
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=(\frac{2 E}{R+2 r})^{2} R=(\frac{2 \times E}{2+2 r})^{2} \times 2=2 W $
BETA
