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

Related Mcqs:

1. 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
   E. 0.60

2. 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
   E. area and time

3. When heat is transferred form hot body to cold body, in a straight line, without affecting the intervening medium, it is referred as heat transfer by __________________?

   A. conduction
   B. convection
   C. radiation
   D. conduction and convection
   E. convection and radiation

4. Emissivity of a white polished body in comparison to a black body is________________?

   A. higher
   B. lower
   C. same
   D. depends upon the shape of body
   E. none of the above

5. The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body. This statement is known as_________________?

   A. Krichoff’s law
   B. Stefan’s law
   C. Wien’ law
   D. Planck’s law
   E. Black body law

6. Two balls of same material and finish have their diameters in the ratio of 2 : 1 and both are heated to same temperature and allowed to cool by radiation. Rate of cooling by big ball as compared to smaller one will be in the ratio of____________________?

   A. 1 :1
   B. 2: 1
   C. 1 : 2
   D. 4 : 1
   E. 1 : 4

7. Total emissivity of polished silver compared to black body is___________________?

   A. same
   B. higher
   C. more or less same
   D. very much lower
   E. very much higher

8. 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
   E. l/T

9. The energy distribution of an ideal reflector at higher temperatures is largely in the range of ___________________?

   A. shorter wavelength
   B. longer wavelength
   C. remains same at all wavelengths
   D. wavelength has nothing to do with it
   E. none of the above

10. According to Wien’s law, the wavelength corresponding to maximum energy is proportion to ________________?

    A. absolute temperature (T)
    B. I2
    C. f
    D. t
    E. 1/r