What is the temperature at which a black body radiates heat at the rate of one kilowatt per unit area ?
(Stefan 's constant `sigma` = `5.7 xx 10^(-8)` S.Iunits)

A spherical black body of 5 cm radius is maintained at a temperature of 327^@C . Then the power radiated will be ( sigma = 5.7 xx 10^(-8) SI unit )

The surface of a black body is at a temperature 727^(@)C and its cross section is 1m^(2) Heat radiated from this surface in one minute in Joules is (Stefan's constant =5.7 xx 10^(-8) W//m^(2)//k^(4)) .

Energy is emitted from a hole in an electric furnace at the rate of 20 watt when furnace is at 227^@C . Find the area of the hole, sigma = 5.7 xx 10^-8 S.I . units.

Calculate the energy radiated in 30 seconds by perfectly black sphere of radius5cm maintained at 127^@C . (Stefan's constant s = 5.7 xx 10^-8 J//m^2sk^4)

A body having surface area 5 cm^2 and temperature of 727^@C radiates 300 J of energy per minutes. What is its emissivity?(Stefan's constanta sigma=5.7xx10^-8 J//mk^4 )

A 100 watt filament loses all its power by radiation when it is heated to a temperature of 2500 K. If the diameter of the filament is 0.2 mm and the surface emissivity of the filament is 0.5, find the length of the filament. (Stefan's constant sigma = 5.67 xx10^-8 W/m^2k^4 )

The surface temperature of a black body is 1200 K. What is the wavelength corresponding to maximum intensity of emission of radiation if Wien's constant b = 2.892 xx 10^-3 mk ?

Assuming that the sun radiates as a black body, calculate the energy radiated per minute by unit area of its surface. Surface temperature of the sun = 5727^@C and Stefan's constant = 5.7 xx10^-8 Jm^-2K^-4s^-1 .