Question

In two experiments with a continuous flow calorimeter to determine the specific heat capacity of a liquid, an input power of $60$ W produced a rise of $10$ K in the liquid. When the power was doubled, the same temperature rise was achieved by making the rate of flow of liquid three times faster. The power lost to the surrounding in each case was :

• A. $20$ W
• B. $30$ W
• C. $40$ W
• D. $120$ W

Answer 1

The correct option is B

$30$ W

Let the power lost to surrounding is $Q$
$\therefore 60-Q=\left(\frac{dm}{dt}\right)S\left(10\right)$
and $20-Q=3\left[\left(\frac{dm}{dt}\right)S\right(10\left)\right]\therefore \frac{120-Q}{60-Q}=3\therefore Q=30W$