A copper sphere has a surface area of `3.142 xx 10^-2m^2` and its emissivity is 0.018. Find the energy lost by the sphere per second when its temperature is `100^@C`. (`sigma = 5.67 xx 10^-8 W/m^2k^4`.)

A small blackened solid copper sphere of radius 2.5cm is placed in an evaculated chamber. The temperature of the chamber is maintained at 100^@C . At what rate energy must be supplied to the copper sphere to maintain its temperature at 110^@C . ( sigma = 5.76 xx 10^-8 Js^-1m^-2K^-4 ) Treat sphere as black body.

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 )

Calculate the energy radiated in one minute by a black body of surface area 100 cm^2 when it is maintained at 227^@C ( sigma= 5.67 xx 10^-8 J/m^2sK^4 )

A body of surface are 15xx10^(-3)m^2 emits 0.3 kcal in 40 second at a temperature 70^(@)C . The emissive power of the surface at that temperature is

A 100 watt filament loses all its power by radiation, when it is heated to a temperature 2500 K. If the diameter of the filament is 0.2mm and emissivity of the filament is 0.5, find the length of the filament to ( sigma = 5.67 xx 10^-8 J//m^2sK^4 )

A body having a surface area of 50cm^2 radiates 300J of energy per minute at a temperature of 727^(@)C . The emissivity of the body is ( Stefan's constant =5.67xx10^(-8)W//m^2K^4 )

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

A 60 watt filament lamp loses all its energy by radiation from its surface. The emissivity of the surface is 0.5. The area of the surface is 5 xx 10^-5m^3 . Find the temperature of the filament ( sigma = 5.67 xx 10^-8m^2s^-4K^-4 )