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

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

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

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 emissive power of a body depends upon its___________________?

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

40% of incident radiant energy on the surface of a thermally transparent body is reflected back. If the transmissivity of the body be 0.15, then the emissivity of surface is____________________?

A. 0.45
B. 0.55
C. 0.40
D. 0.75

The total emissivity power is .defined as the total amount of radiation emitted by a black body per unit_______________?

A. Temperature
B. Thickness
C. Area
D. Time

Depending on the radiating properties, a body will be black when_________________?

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

According to Stefan’s law, the total radiation from a black body per second per unit area is proportional to____________________?

A. Absolute temperature
B. T2
C. T5
D. T

The thermal diffusivities for solids are generally__________________?

A. Less than those for gases
B. Jess than those for liquids
C. More than those for liquids and gases
D. More or less same as for liquids and gases