149586 The radiation emitted by a star $A$ is 10,000 times that of the sun. If the surface temperatures of the sun and the star $A$ are $6000 \mathrm{~K}$ and $2000 \mathrm{~K}$ respectively, the ratio of the radii of the star $A$ and the sun is

149587 A black body of mass $34.38 \mathrm{~g}$ and surface area $19.2 \mathrm{~cm}^{2}$ is at an initial temperature of $400 \mathrm{~K}$. It is allowed to cool inside an evacuated enclosure kept at constant temperature $300 \mathrm{~K}$. The rate of cooling is $0.04{ }^{\circ} \mathrm{C} / \mathrm{s}$. The specific heat of the body in $\mathrm{J} \mathrm{kg}^{-1} \mathrm{~K}^{-1}$ is
(Stefan's constant, $\sigma=5.73 \times 10^{-8} \mathrm{Wm}^{-2} \mathrm{~K}^{-4}$ )

149588 A black body radiates energy at the rate of $E$ $\mathrm{W} / \mathrm{m}^{2}$ at a high temperature $T K$. When the temperature is reduced to $\left(\frac{T}{2}\right) K$, the radiant energy is

149589 Two stars emit maximum radiation at wavelength $4000 \mathrm{~A}^{\circ}$ and $6000 \mathrm{~A}^{\circ}$ respectively. The ratio of their temperatures is

149586 The radiation emitted by a star $A$ is 10,000 times that of the sun. If the surface temperatures of the sun and the star $A$ are $6000 \mathrm{~K}$ and $2000 \mathrm{~K}$ respectively, the ratio of the radii of the star $A$ and the sun is

149587 A black body of mass $34.38 \mathrm{~g}$ and surface area $19.2 \mathrm{~cm}^{2}$ is at an initial temperature of $400 \mathrm{~K}$. It is allowed to cool inside an evacuated enclosure kept at constant temperature $300 \mathrm{~K}$. The rate of cooling is $0.04{ }^{\circ} \mathrm{C} / \mathrm{s}$. The specific heat of the body in $\mathrm{J} \mathrm{kg}^{-1} \mathrm{~K}^{-1}$ is
(Stefan's constant, $\sigma=5.73 \times 10^{-8} \mathrm{Wm}^{-2} \mathrm{~K}^{-4}$ )

149588 A black body radiates energy at the rate of $E$ $\mathrm{W} / \mathrm{m}^{2}$ at a high temperature $T K$. When the temperature is reduced to $\left(\frac{T}{2}\right) K$, the radiant energy is

149589 Two stars emit maximum radiation at wavelength $4000 \mathrm{~A}^{\circ}$ and $6000 \mathrm{~A}^{\circ}$ respectively. The ratio of their temperatures is

149586 The radiation emitted by a star $A$ is 10,000 times that of the sun. If the surface temperatures of the sun and the star $A$ are $6000 \mathrm{~K}$ and $2000 \mathrm{~K}$ respectively, the ratio of the radii of the star $A$ and the sun is

149587 A black body of mass $34.38 \mathrm{~g}$ and surface area $19.2 \mathrm{~cm}^{2}$ is at an initial temperature of $400 \mathrm{~K}$. It is allowed to cool inside an evacuated enclosure kept at constant temperature $300 \mathrm{~K}$. The rate of cooling is $0.04{ }^{\circ} \mathrm{C} / \mathrm{s}$. The specific heat of the body in $\mathrm{J} \mathrm{kg}^{-1} \mathrm{~K}^{-1}$ is
(Stefan's constant, $\sigma=5.73 \times 10^{-8} \mathrm{Wm}^{-2} \mathrm{~K}^{-4}$ )

149588 A black body radiates energy at the rate of $E$ $\mathrm{W} / \mathrm{m}^{2}$ at a high temperature $T K$. When the temperature is reduced to $\left(\frac{T}{2}\right) K$, the radiant energy is

149589 Two stars emit maximum radiation at wavelength $4000 \mathrm{~A}^{\circ}$ and $6000 \mathrm{~A}^{\circ}$ respectively. The ratio of their temperatures is

149586 The radiation emitted by a star $A$ is 10,000 times that of the sun. If the surface temperatures of the sun and the star $A$ are $6000 \mathrm{~K}$ and $2000 \mathrm{~K}$ respectively, the ratio of the radii of the star $A$ and the sun is

149587 A black body of mass $34.38 \mathrm{~g}$ and surface area $19.2 \mathrm{~cm}^{2}$ is at an initial temperature of $400 \mathrm{~K}$. It is allowed to cool inside an evacuated enclosure kept at constant temperature $300 \mathrm{~K}$. The rate of cooling is $0.04{ }^{\circ} \mathrm{C} / \mathrm{s}$. The specific heat of the body in $\mathrm{J} \mathrm{kg}^{-1} \mathrm{~K}^{-1}$ is
(Stefan's constant, $\sigma=5.73 \times 10^{-8} \mathrm{Wm}^{-2} \mathrm{~K}^{-4}$ )

149588 A black body radiates energy at the rate of $E$ $\mathrm{W} / \mathrm{m}^{2}$ at a high temperature $T K$. When the temperature is reduced to $\left(\frac{T}{2}\right) K$, the radiant energy is

149589 Two stars emit maximum radiation at wavelength $4000 \mathrm{~A}^{\circ}$ and $6000 \mathrm{~A}^{\circ}$ respectively. The ratio of their temperatures is