Q. According to Stefan-Boltzmann law of thermal radiation

View solution

Q. Calculate the radiant flux density from a black surface at 400 degree Celsius?

View solution

Q. If the emitted radiant energy is to be doubled, to what temperature surface of black body needs to be raised? Take radiant flux density as 11631.7 W/m 2.

View solution

Q. A furnace having inside temperature of 2250 has a glass circular viewing of 6 cm diameter. If the transmissivity of glass is 0.08, make calculations for the heat loss from the glass window due to radiation

View solution

Q. The value of radiation coefficient or the Stefan-Boltzmann constant is

View solution

Q. What is the wavelength band for Ultraviolet rays?

View solution

Q. A black body of total area 0.045 m² is completely enclosed in a space bounded by 5 cm thick walls. The walls have a surface area 0.5 m² and thermal conductivity 1.07 W/ m K. If the inner surface of the enveloping wall is to be maintained at 215 degree Celsius and the outer wall surface at 30 degree Celsius, calculate the temperature of the black body

View solution

Q. What is the wavelength band for solar radiation?

View solution

Q. The relationship (Wavelength)MAX T = constant, between the temperature of a black body and the wavelength at which maximum value of monochromatic emissive power occurs is known as

View solution

Q. A body at 500 K cools by radiating heat to ambient atmosphere maintained at 300 K. When the body has cooled to 400 K, the cooling rate as a percentage of original rate is about

View solution

Q. Two spheres A and B of same material have radius 1 m and 4 m, and temperatures 4000 K and 2000 K respectively. Then the energy radiated by sphere A is

View solution

Q. A small body has a total emissive power of 4.5 kW/m². Determine its surface temperature of maximum emission

View solution

Q. A small black body has a total emissive power of 4.5 k W/m². In which range of the spectrum does this wavelength fall?

View solution

Q. The sun emits maximum radiation of 0.52 micron meter. Assuming the sun to be a black body, Calculate the surface temperature of the sun

View solution

Q. A furnace emits radiation at 2000 K. Treating it as a black body radiation, calculate the wavelength at which emission is maximum

View solution

Q. Four identical pieces of copper painted with different colors of paints were heated to the same temperature and then left in the environment to cool. Which of the following paint will give fast cooling?

View solution

Q. A surface for which emissivity is constant at all temperatures and throughout the entire range of wavelength is called

View solution

Q. If radiant energy EB emitted by the black surface strikes the non-black surface. If non-black surface has absorptivity α, it will absorb how much radiations?

View solution

Q. If two surfaces are at the same temperature, then the conditions correspond to mobile thermal equilibrium for which the resultant interchange of heat is zero are

View solution

Q. The absorptivity of black body equals to

View solution