EXERCISE

A hot body cools from $85°\mathrm{C}$ to $75°\mathrm{C} T$ in time $T_1$, from $75°\mathrm{C}$ to $65°\mathrm{C}$ in time $T_2$ and from $65°\mathrm{C}$ to $55°\mathrm{C}$ in time $T_3$, then (temperature of surrounding $=30°\mathrm{C}$)

The temperature and the surface area of a body are $227°\mathrm{C}$ and $0.15{ \mathrm{m}}^2$ respectively. If its transmitting power is negligible and reflecting power is $0.5$, the thermal power of the body is

A body cools by Newton's law of cooling. The surrounding temperature is $25°\mathrm{C}$. The temperature of the body falls from $60°\mathrm{C}$ to $50°\mathrm{C}$ in $10 \min$. The temperature at the end of next $10 \min$ is

Assuming the sun to be a spherical body of radius $R$ at a temperature of $T \mathrm{K}$, evaluate the total radiant power, incident on the earth, at a distance $r$ from the sun:

(radius of earth is $r_0$)

A black body at $1227°\mathrm{C}$ emits radiations with maximum intensity at a wavelength of $5000\AA .$ If the temperature of the body is increased by $1000°\mathrm{C},$ the maximum intensity will be at

Water of volume $2 \mathrm{litre}$ in a container is heated with a coil of $1 \mathrm{kW}$ at $27°\mathrm{C}$. The lid of the container is open and energy dissipates at the rate of $160 \mathrm{J}/\mathrm{s}$. In how much time temperature will rise from $27°\mathrm{C}$ to $77°\mathrm{C}$ (Given specific heat of water is $4.2\mathrm{km}/\mathrm{kg}]$

A black and a yellow body at room temperature are thrown into a furnace at very high temperature. Select the correct statement.