Two identical batteries each of e.m.f 2V and internal resistance

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Two identical batteries each of e.m.f 2V and internal resistance 1Ω 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

1. 3.2 W
2. 2.0 W
3. 1.28 W
4. (8/9) W

Correct Option: 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. 2Ω. Hence power devloped across the resistacne R will be