An indirectly heated filament is radiating maximum energy of wavelength `2.16xx10^-5cm`. Find the net amount of heat energy lost per second per unit area, the temperature of the surrounding air is `13^@C`. Given `b=0.288cm-K.sigma=5.77xx10^-5erg//s-cm^(2)-K^(4)`).

A heated filament of a bulb is radiating maximum energy at wavelength 3.14 xx 10^(-5) cm. Determine the total amount of energy lost per second per unit area by the filament if the temperature of the surrounding air is 20^@C . Take, b = 0.288 cm K sigma = 5.77 xx 10^(-5) erg s^(-1) cm^(-2) K^(-4)

Two stars radiate maximum energy at wavelengths 3.6xx10^(-5)cm and 4.8xx10^(-5)cm respectively. The ratio of their temperature is

A sphere of radius 15 cm is at a temperature of 215^@C . Find the maximum amount of heat which may be lost per second by radiation when the sphere is placed in an enclosure at 25^@C . Take, sigma = 5.67 xx 10^(-8) Wm^(-2) K^4

Three cubes of sides 1,2,3 cm are at constant temperature of 100^(@)C . Then the amount of heat lost per second by them are in the ratio

Calculate the maximum amount of heat which may be lost per second by radiation by a sphere 14cm in diameter at a temperature of 227^(@)C , when placed in an enclosure at 27^(@)C . Given Stefan's constant = 5.7 xx 10^(-8)Wm^(-2)K^(-4) .

If the sun's surface radiates heat at 6.3 xx 10^(7) Wm^(-2) . Calculate the temperature of the sun assuming it to be a black body (sigma = 5.7 xx 10^(-8)Wm^(-2)K^(-4))

A spherical ball oof surface area 20cm^(@) absorbs any radiation that falls on it. It is susoended in a closed box maintained at 57^(@)C . (a) Find the amount of radiation falling on the ball per second. (b0 Find the net rate of heat flow to or from the ball at an instant when its temperature is 200^(@)C . Stefan constant =6.0xx10^(-s)Wm^(-2)K^(-4) .

At what temperature will the filament of 100 W lamp operate if it is supposed to be perfectly black of area 1 cm^(2) . Given sigma = 5.67 xx 10^(-5) erg cm^(-2) s^(-1) K^(-4) .

Assume that the total surface area of a human body is 1-6m^(2) and that it radiates like an ideal radiator. Calculate the amount of energy radiates per second by the body if the body temperature is 37^(@)C . Stefan contant sigma is 6.0xx10^(-s)Wm^(-2)K^(-4) .