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.

A copper sphere is suspended in an evacuated chamber maintained at 300K . The sphere is maintained at a constant temperature of 500K by heating it electrically. A total of 210W of electric power is needed to do it. When the surface of the copper sphere is completely blackened, 700W 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 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 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 copper sphere is maintained at 500 K temperature by connecting it to a battery of emf V_(1) = 100 V (see figure). The surrounding temperature is 300 K. When half the surface of the copper sphere is completely blackened (so that the surface behaves almost like a black body), a cell of emf V_(2) = 141 V is needed to maintain its temperature at 500 K. Calculate the emissivity of the copper surface.

A spherical tungsten pieces of radius 1.0cm is suspended in an evacuated chamber maintained at 300K . The pieces 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 pieces of radius 1.0cm is suspended in an evacuated chamber maintained at 300K . The pieces 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) .

Two identical spheres A and B are suspended in an air chamber which is maintained at a temperature of 50^@C . Find the ratio of the heat lost per second from the surface of the spheres if a. A and B are at temperatures 60^@C and 55^@C , respectively. b. A and B are at temperatures 250^@C and 200^@C , respectively.

Two identical spheres A and B are suspended in an air chamber which is maintained at a temperature of 50^@C . Find the ratio of the heat lost per second from the surface of the spheres if a. A and B are at temperatures 60^@C and 55^@C , respectively. b. A and B are at temperatures 250^@C and 200^@C , respectively.