Question

Two cells, each of emf 2 V and internal resistance 1 $\Omega$ are given. The maximum heat that can be produced in a resistance of 0.5 $\Omega$ with the help of given two cells is:

• A. 4.2 W
• B. 2.9 W
• C. 2.0 W
• D. 1 W

Answer 1

Answer: (C)

2.0 W

Given : $R=0.5\Omega$ $r=1\Omega$ $E=2$ volts

For maximum heat to be produced, $r_{eq}=R$

$\therefore$ $r_{eq}=0.5\Omega$

This can be possible when the two cells are connected in parallel.

Thus equivalent emf of two cell in parallel connection $E_{eq}=E=2$ volts

$\therefore$ Maximum power produced $P_{max}=\frac{E_{eq}^2}{4R}=\frac{2^2}{4\times 0.5}=2.0$ watts