A spherical tungsten piece of radius `1.0cm` is suspended in an evacuated chamber maintained at `300K`. The piece is maintained at `1000K` by heating it electrically. Find the rate at which the electrical energy must be supplied. The emissivity of tungsten is `0.30` and the Stefan constant sigma is `6.0xx10^(-s)Wm^(-2)K^(-4)` .

A spherical tungsten pices of radius 1.0cm is suspended in an evacuated chamber maintained at 300K. The pices is maintained at 1000K by heating it electrically. Find the rate at which the electrical energy must be supplied. The emissivity of tungsten is 0.30 and the Stefan constant sigma is 6.0xx10^(-s)Wm^(-2)K^(-4) .

A spherical tungsten piece of radius (1)/(sqrt(pi)) cm is suspended in an evacuated chamber maintained at 200 K . The piece is maintained at 400 K by heating it electrically. Find the rate at which the electrial energy must be supplied. The emissivity of tungsten is 0.50 , the Steafan constant sigma is 6.0 xx 10^(-8) W//m^(2)-K^(4)

A spherical ball of radius 1cm coated with a metal having emissivity 0.3 is maintained at 1000 K temperature and suspended in a vacuum chamber whose walls are maintained at 300 K temperature. Find rate at which electrical energy is to be supplied to the ball to keep its temperature constant.

A copper sphere is suspended in an evacuated chamber maintained at 300K. The sphere is maitained at a constant temperature of 500K by heating it electrically. A total of 210W is electric power is needed to do it. When the surface of the copper sphere is completely blackned, 700W is needed to maintain the same temperature of the sphere. Calculate the emissivity of copper.

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^(-8) W m^(-2)K^(-4)

A copper sphere is suspended in an evacuated chamber maintained at 300 k. The sphere is maintained at a constant temperature of 500 K by heating it electrically. A total of 210 W of electric power is needed to do it. When the surface of the copper shphere is completely blackened, 700 W is needed to maintain the same temperature of the sphere. Calculate the emissivity of copper.

A copper sphere is suspended in an evacuated chamber maintained at 300 K . The sphere is mantained at a constant temperature of 500 K by heating it electrically. A total of 300 W of electric power is needed to do it. When half of the surface of the copper sphere is completely blackened, 600W is needed to maintain the same temperature of the the sphere. Calculate the emissivity of copper.

A hot body at 800^@C is radiating 500 J of energy per minute. Calculate the surface area of the body if emissivity is 0.23 and Stefan's constant is 5.67 xx 10^(-8) Wm^(-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)

An electric bulb with tungsten filament having an area of 0.25 cm^(2) is raised to a temperature of 3000 K , when a current passes through it. Calculate the electrical energy being consumed in watt, if the emissivity of the filament is 0.35. Stefan's constant, sigma = 5.67 xx 10^(-5) erg^(-1) cm^(-2) K^(-4) . If due to fall in main voltage the fialment temperature falls to 2500 K, what will be wattage of the bulb?