A thin circulr disc has a concentric hole in it. On heating the diameter of hole will

Related MCQs

• A piece of metal with a circular hole is heated. If the metal expands on heating the diameter of the hole will
• Two large closely spaced concentric spheres (both of which are perfect black body radiators) are maintained at temperatures of 127?C and 27?C respectively. The space in between the two spheres is evacuated. Taking Stefan Boltzmann constant as 5.67 x 108 watt m2K the rate of radiation in watts per sq. m between the two spheres is approximately
• A shpere, a cube and a disc all of the same material, quality and volume are heated to 900K and left in air. Which of these will have the lowest rate of cooling
• 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 rate of heat transfer through a pipe wall is given by, q = 2π k (Ti- T0)/ln (ri /r0). For cylinder of very thin wall, q can be approximated by
• 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.
• A cube, sphere & a thin circular plate (all having same mass and made of same material) are all heated to 300°C and allowed to cool in natural air. Which one will cool the slowest?
• The maximum heat transfer co-efficient from steam heating will be attained when the steam is:
• The actual temperature drop across the heating surface of an evaporator depends on the
• 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