A small hole is made in a hollow sphere whose walls are at `723^(@)C`. Find the total energy radiated per seond per `cm^(2)`. Given Stenfan's constant `= 5.7 xx 10^(-5) erg cm^(-2) s^(-1) K^(-4)`.

A pinhole is made in a hollow sphere of radius 5cm whose inner wall is at temperature 727^(@)C . Find the power radiated per unit area. [Stefan's constant sigma=5.7xx10^(-8)J//m^(2)sK^(4) , emissivity (e)=0.2 ]

A small hole is made in a hollow enclosure whose walls are maintained at a temperature of 1000 K. The amount of energy being emitted per square metre per second is :

A blackened solid copper sphere of radius 2 cm is placed in an evacuated enclosure whose walls are kept at 100^(@)C . At what rate must energy be supplied to the sphere to keep its temperature constant at 127^(@)C ? Stefan constant = 5.67xx 10^(-8)Jm^(-2)K^(-4).

Calculate the temperature at which a perfect black body radiates at the rate of 1 W cm^(-2) , value of Stefan's constant, sigma = 5.67 xx 10^(-5) W m^(-2) K^(-8)

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) .

Consider the sun to be a perfect sphere of radius 6.8 xx 10^(8)m . Calculate the energy radiated by sun in one minute. Surface temperature of the sun = 6200 K . Stefan's constant = 5.67 xx 10^(-8) J m^(-2) s^(-1) 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) .

Calculate the energy radiated in one minute by a blackbody of surface area 200 cm^2 at 127 ""^(@)C ( sigma= 5.7 xx 10^(-8) J m^(-2) s^(-1) K^(-4))

A metallic ball of surface area 300 cm^2 at a temperature of 227^@C is placed in a container at 27^@C . Calculate the rate of loss of heat radiation by the ball if emissivity of ball is 0.3, sigma = 5.67 xx 10^(-5) erg cm^(-2) s^(-1) K^(-4) .

An electric bulb with a tungsten filament has an area of 0.20 cm^2 and is raised to a temperature of the bulb to 3000 K emissivity of the filament is 0.40 and Stefan's constant is 5.7 xx 10^(-5) erg s^(-1) cm^(-1) K^(-4) . The electrical energy consumed by the bulb is E_1 watt. If due to fall in voltage, the temperature of the filament falls to 2800 K, then the wattage of the bulb is E_2 watt. Calculate the value of E_1 - E_2 , close to nearest integer.