A spherical black body with a radius of $12\;{\rm{ cm}}$ radiates ${\rm{450\; Watt}}$ power at ${\rm{500\; K}}{\rm{.}}$If the radius were halved and the temperature doubled, the power radiated in watt would be

If wavelength of maximum intensity of radiations emitted by the sun and the moon are $0.5 imes {10^{ - 6}}m$ and ${10^{ - 4}}m$ respectively, the ratio of their temperature is

A black body emits maximum radiation at a wavelength of 500 nm. If the temperature of the black body is doubled, what will be the wavelength at which maximum radiation is emitted? (Wien’s constant, $b = 2.88 imes 10^6$ nmK)

A thin square steel plate with each side equal to 10 cm is heated by a blacksmith. The rate of radiated energy by the heated plate is 1134 W . The temperature of the hot steel plate is (Stefan’s constant $\sigma = 5.67 imes {10^{ - 8}}watt\,\,{m^{ - 2}}{K^{ - 4}}$ , emissivity of the plate = 1)

Newton’s law of cooling holds good only, if the temperature difference between the body and the surroundings is

Let there be four articles having colours blue, red, black and white. When they are heated together and allowed to cool, which article cool at the earliest

If the maximum intensity of 396 for a black body is found at 2.65 $\mu m$, the temperature of the radiating body is (wien’s constant = $2.9 imes {10^{ - 3}}mK$)

The temperature of a piece of metal is increased from 27$^ \circ C$ to 84$^ \circ C$. The rate at which energy is radiated is increased to

Two spheres made of same material have radii in the ratio 2:1. If both the spheres are at same temperature, then what is the ration of heat radiation energy emitted per second by them?

What is the primary source of ultraviolet radiation on Earth?

A body cools from ${62^0}C$ to ${50^0}C$ in 10 min and to ${42^0}C$ in the next 10 min. The temperature of the surrounding is