With increase in temperature, the total emissivity of conductors

Related MCQs

• The statement that the emissivity and absorptivity of a surface is surrounded by its own temperature are the same for both monochromatic and total radiation, is known as
• The total emissivity power is .defined as the total amount of radiation emitted by a black body per unit
• The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m2 . The approximate surface temperature (K) is (Stefan-Boltzmann constant = 5.67 × 10-8 W/m2 .K4 )
• Total emissivity of polished silver compared to black body is
• While the total emissivity of a perfect black body is unity, the same for a real body is
• Two parallel opposed, infinite black planes are maintained at 300?C and 400?C respectively. If the temperature difference is doubled by increasing the temperature from 400?C to 500?C, the heat exchange rate will increase by a factor of about
• Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer coefficient is „3k/l’. If the wall temperature on the outside is held at 25°C, what is the inside wall temperature in degree centigrade?
• If the thermal conductivity of a wall material is independent of temperature, the steady state temperature distribution in the very large thin plane wall having steady, uniform surface temperature follows __________ law.
• The radiation heat flux from a heating element at a temperature of 800°C, in a furnace maintained at 300°C is 8 kW/m2 . The flux, when the element temperature is increased to 1000°C for the same furnace temperature is
• A long iron rod initially at a temperature of 20°C has one end dipped in boiling water (100°C) at time, t = 0. The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The temperature at a distance 100 mm from the dipped end becomes 40°C at time, t = 200 s. The same temperature is achieved at a distance of 200 mm from the dipped end at time