A body of surface area `10 cm^2` and temperature `727^@C` emits 300 J of energy per minutes.Find the emissivity.

A body having surface area 5 cm^2 and temperature of 727^@C radiates 300 J of energy per minutes. What is its emissivity?(Stefan's constanta sigma=5.7xx10^-8 J//mk^4 )

A metal ball of surface area 200 cm^(2) and temperature 527^(@)C is surrounded by a vessel at 27^(@)C . If the emissivity of the metal is 0.4, then the rate of loss of heat from the ball is (sigma = 5.67 xx10^(-8)J//m^(2)-s-k^(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 )

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

If a body cools from 80^@C to 50^@ C at room temperature of 25^@ C in 30 minutes.Find the temperature of the body after 1 hour.

A black body of mass 32g, specific heat = 0.1 cal^@c and area 8 cm^2 at a temperature of 300^C is kept in an enclosure maintained at 0^C . If the body cools at the rate of 0.35 ^@C//s , calculate Stefan’s constant. J = 4.18 joule/cal.

A black body is at a temperature of 527^@C , to radiate twice as much energy per second its temperature must be increased to

A black rectangular surface of area A emits energy E per second at 27^circC . If length and breadth are reduced to one third of initial value and temperature is raised to 327^circC , then energy emitted per second becomes

The surface of a black body is at a temperature 727^(@)C and its cross section is 1m^(2) Heat radiated from this surface in one minute in Joules is (Stefan's constant =5.7 xx 10^(-8) W//m^(2)//k^(4)) .