Question

In the circuit shown, the heat produced in 5$\Omega$ resistor is 10 calorie/sec. The heat produced/sec in 4$\Omega$ resistor will be :

• A. 1 cal
• B. 2 cal
• C. 3 cal
• D. 4 cal

Answer 1

The correct option is B 2 cal

Given : $P=10$ cal/s $R=5$ $\Omega$

Voltage across 5 ohm resistor, $V=\sqrt{RP}=\sqrt{5\times 10}=5\sqrt{2}$ volts

Thus voltage across 4 ohm resistor $V^{\prime }=\frac{4}{4+6}{V}^{\prime }=\frac{4}{10}\times 5\sqrt{2}=2\sqrt{2}$ volts

$\therefore$ Heat produced per sec in 4 ohm resistor, $P^{\prime }=\frac{(V^{\prime }{)}^2}{4}=\frac{8}{2}=2$ cal/sec