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__________________?

Related Mcqs:

1. Stefan-Boltzmann law which describes the radiation heat transfer states that, it is proportional to (where, t = temperature in °C T = absolute temperature in ° K) ?

   A. t4
   B. T4
   C. 1/t4
   D. 1/T4

2. The variation of thermal conductivity of a metal with temperature is often correlated using an expression of the form K = K0 + at, where, K is the thermal conductivity and T is the temperature (in °K). The units of ‘a’ in SI system will be________________?

   A. W/m.k
   B. W/m
   C. W/m.k2
   D. None, ‘a’ is just a number

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

   A. 0°K
   B. 0°C
   C. 100°C
   D. Room temperature

4. 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

5. The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)?

   A. αT
   B. α × 1/T
   C. α T4
   D. Independent of T

6. 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

7. 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

8. For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally ?

   A. Decreases
   B. Increases
   C. Remains unchanged
   D. Increases exponentially

9. Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is ________________ law?

   A. Stefan’s
   B. Dalton’s
   C. Wien’s
   D. Kirchoff’s

10. Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer coefficient is „3k/l’. If the wall temperature on the outside is held at 25°C, what is the inside wall temperature in degree centigrade ?

    A. 35.5
    B. 43.75
    C. 81.25
    D. 48.25