Questions
61
Total emissivity of polished silver compared to black body is
Answer: Very Much Lower
63
The thermal diffusivities for solids are generally
Answer: more than those for liquids and gases
64
According to Stefan’s law, the total radiation from a black body per second per unit area is proportional to
Answer: t
65
The total emissivity power is .defined as the total amount of radiation emitted by a black body per unit
Answer: Time
66
The ratio of the energy absorbed by the body to total energy falling on it is called
Answer: Absorptive Power
69
In regenerator type heat exchanger, heat transfer takes place by
Answer: flow of hot and cold fluids alternately over a surface
70
If the temperature of a solid surface changes form 27°C to 627°C, then its emissive power changes in the ratio of
Answer: 81
