Radiation energy is emitted by all the substances, which are above____________________?

Related Mcqs:

1. The thermal radiation emitted by a body is proportional to Tn, where T is its absolute temperature. The value of ‘n’ is exactly 4 for__________________?

   A. Black painted bodies only
   B. All bodies
   C. Polished bodies only
   D. A black body

2. Radiant energy received by a body is proportional to (where, d = the distance between the object emitting radiation and that receiving it.) ?

   A. √d
   B. d
   C. d2
   D. d1.5

3. Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer cannot take place____________________?

   A. Between two bodies in physical contact with each other
   B. Between two bodies not in physical contact with each other
   C. From one part of a body to the another part of the same body
   D. Both B & C

4. The absorptivity of a grey body at a given temperature _____________ with increasing wavelength of radiation?

   A. Increases
   B. Decreases
   C. Remain constant
   D. May increase or decrease; depends on the material

5. A perfect black body is a perfect _____________ of radiation?

   A. Absorber
   B. Emitter
   C. Both A. & B.
   D. Neither A. nor B.

6. Electro-magnetic spectrum range, which is important for radiation varies from _____________ microns?

   A. 1 to 100
   B. 0.5 to 50
   C. 10 to 100
   D. 100 to 1000

7. The range of electromagnetic spectrum important in heat transfer by radiation is ______________ microns?

   A. 0.38-0.78
   B. 0.5-50
   C. 100-1000
   D. 5-50

8. The rate of emission of radiation by a body does not depend upon the__________________?

   A. Wavelength of radiation
   B. Surface temperature of the body
   C. Nature of the surface
   D. Shape and porosity of the body

9. 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. 11.2 kW/m2
   B. 12.0 kW/m2
   C. 14.6 kW/m2
   D. 16.5 kW/m2

10. The statement that “maximum wavelength of radiation is inversely proportional to the temperature” is ______________ law?

    A. Stefan-Boltzmann’s
    B. Planck’s
    C. Wien’s displacement
    D. None of these