Question

In the circuit shown in figure the heat produced in the $5\Omega$ resistor due to the current flowing through it is 10 cal/s. The heat generated in the $4\Omega$ resistor is

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

Answer 1

Answer: (B)

2 cal/s

Answer 2

Since, resistance in upper branch of the circuit is twice the
resistance in lower branch. Hence, current there will be half
$P_4=(i/2)^2(4) \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, (p=i^2R)$
$P_5 = (i)^2(5)$
or $\, \, \, \, \, \, \, \, \, \, \, \frac{P_4}{P_5} = \frac{1}{5}$
$P_4 = \frac{P_5}{5} = \frac{10}{5} = 2 \, cal/s$
$\therefore \,$Correct option is (b)