The emissive power of a body depends upon its___________________?

A. Temperature
B. Wave length
C. Physical nature
D. All of the above

The ratio of the energy absorbed by the body to total energy falling on it is called_________________?

A. Absorptive power
B. Emissive power
C. Absorptivity
D. Emissivity

The amount of radiation mainly depends on___________________?

A. Nature of body
B. Temperature of body
C. Type of surface of body
D. All of the above

Absorptivity of a body will be equal to its emissivity___________________?

A. At all temperatures
B. At one particular temperature
C. When system is under thermal equi-librium
D. At critical temperature

Depending on the radiating properties, body will be transparent when________________?

A. P = 0, x = 0 and a = 1
B. P=l,x = 0,anda = 0
C. P = 0, t= l,anda = 0
D. X = 0, a + p = 1

Two plates spaced 150 mm apart are maintained at 1000°C and 70°C. The heat transfer will take place mainly by ___________________?

A. Convection
B. Free convection
C. Forced convection
D. Radiation

In regenerator type heat exchanger, heat transfer takes place by___________________?

A. Direct mixing of hot and cold fluids
B. A complete separation between hot and cold fluids
C. Flow of hot and cold fluids alternately over a surface
D. Generation of heat again and again

If the temperature of a solid surface changes form 27°C to 627°C, then its emissive power changes in the ratio of___________________?

A. 3
B. 6
C. 9
D. 27

A perfect black body is one which_______________?

A. Is black in colour
B. Reflects all heat
C. Transmits all heat radiations
D. Abslprbs heat radiations of all wave lengths falling on it

Planck’s law holds good for________________?

A. Black bodies
B. Polished bodies
C. All coloured bodies
D. All of the above