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.

Energy is emitted from a hole in an electric furnace at the rate of 20W when that temperature of the furnace is 727^@C . What is the area of the hole ( sigma = 5.7 xx 10^-8 Js^-1m^-2K^-4 )

The temperature of the filaments of a 100W electric lamp is 2727^@C . The emissivity of the surface of the filament is 0.086 and its radius is 0.5 mm. Find the length of the filament. sigma = 5.7 xx 10^-8 S.I. units.

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 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 )

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 )

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 )

Three 5 kg masses are kept at the vertices of an equilateral triangle each side of 0.25 m. Find resultant gravitational force on any one mass. G= 6.67 xx 10^-11 S.I. units.

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 )