The rays of sun are focussed on a piece of ice through a lens of diameter 5 cm , as a result of which 10 g ice melts in 10 min . The amount of heat received from sun, per unit area per minute is :

Step-by-step solution

Mass of ice melted per minute = 10 10 =1 ~g aligned & Quantity of heat used & aligned Area of lens & = r^2 & =19.625 ~cm ^2 aligned aligned Amount of heat received from sun = 80 19.625 =4 cal / cm ^2 ~min Latent heat of fusion =80