A. grey body
B. brilliant white polished body
C. red hot body
D. black body
E. none of the above
Related Mcqs:
- 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 - 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
E. 81 - The value of the wavelength for maximum emissive power is given by ___________________?
A. Wien’s law
B. Planck’s law
C. Stefan’s law
D. Fourier’s law
E. Kirchhoff’s law - The emissive power of a body depends upon its___________________?
A. temperature
B. wave length
C. physical nature
D. all of the above
E. none of the above - A grey body is one whose absorptivity _________________?
A. varies with temperature
B. varies with the wave length of incident ray
C. varies with both
D. does not vary with temperature and wave length of the incident ray
E. there is no such criterion - 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
E. for a polished body - 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 - According to Stefan-Boltzmann law, ideal radiators emit radiant energy at a rate proportional to___________________?
A. absolute temperature
B. square of temperature
C. fourth power of absolute temperature
D. fourth power of temperature
E. cube of absolute temperature - 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 - 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
