Current Electricity - Result Question 86
91. 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
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======= ####91. 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
c3eec34ec6b1fad69db54a20ad4b2dca40c2aa54 (a) $3.2 W$
(b) $2.0 W$
(c) $1.28 W$
(d) $\frac{8}{9} W$
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Answer:
Correct Answer: 91. (b)
Solution:
- (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 devloped across the resistacne $R$ will be
$ I^{2} R=(\frac{2 E}{R+2 r})^{2} R=(\frac{2 \times 2}{2+2}) \times 2=2 W $
