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.

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 )

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 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 )

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.

The resistance of a wire of length 15.7 m and radius 0.5 mm is 10 Omega . Find the resistivity of the material of the wire.

A wire has radius 0.5 mm and length 62.8 m. If the resistivity of the material of the wire is 5 times 10^(-7) Omega -m , find the resistance of the wire.

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 )

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 )

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.