## HEAT AND MASS TRANSFER MCQ

SECTION-4

##### Q11. The heating effect is caused by the wavelengths when they are in the range of

(a) 100 μ to 150 μ
(b) 0.1 μ to 100 μ
(c) 150 μ to 200 μ
(d) none of the above.

Ans:(b) 0.1 μ to 100 μ

##### Q12. The ratio of the energy absorbed by a body to the total incident radiation energy falling on the body, is called

(a) transmissivity
(b) reflectivity
(c) absorptivity
(d) none of the above.

Ans:(a) transmissivity

##### Q13. The ratio of the energy reflected by a body to the total incident radiation energy falling on the body, is called

(a) transmissivity
(b) reflectivity
(c) absorptivity
(d) none of the above.

Ans:(b) reflectivity

##### Q14. The ratio of the energy transmitted by a body to the total incident radiation energy falling on the body, is called

(a) transmissivity
(b) reflectivity
(c) absorptivity
(d) none of the above.

Ans:(a) transmissivity

##### Q15.A body, which does not transmit any radiations but partly reflects and party absorbs the radiations, is called

(a) opaque body
(b) white body
(c) black body
(d) transparent body.

Ans:(a) opaque body

##### Q16. A hollow sphere with uniform interior temperature and a small hole behaves very nearly as a

(a) opaque body
(b) white body
(c) black body
(d) transparent body.

Ans:(c) black body

##### Q17. Choose the correct statement

(a) The total amount of radiation absorbed by a body per unit time is known as total emissive power.
(b) The value of the wavelength for minimum emissive power is given by Kirchhoff’ s law.
(c) Mathematically Wien’s law is expressed as λ′max × T = constant.
(d) A perfect black body is one which is black in colour.

Ans:(c) Mathematically Wien’s law is expressed as λ′max × T = constant.

##### Q18. Stefan Boltzman Law states that the total emission from a black body per unit area per unit time

(a) varies directly with the absolute temperature
(b) varies inversely with the absolute temperature
(c) varies directly with the square of the absolute temperature
(d) varies directly with the fourth power of the absolute temperature.

Ans:(d) varies directly with the fourth power of the absolute temperature.

##### Q19. In free convection, motion of the fluid is caused

(a) by the weight of the fluid element
(b) by the hydrostatic force of the element
(c) by the buoyancy forces arising from variation in density of the fluid with the temperature
(d) none of the above.

Ans:(c) by the buoyancy forces arising from variation in density of the fluid with the temperature

##### Q20. If h = coefficient of heat transfer, k = thermal conductivity, and l is characteristic linear

dimension then the term hl/kis called
(a) Reynolds number
(b) Nusselt number
(c) Prandtl number
(d) Froude number.

Ans:(b) Nusselt number

1      2      3      4          6      7     8

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##### Read More Sections of Heat Transfer and Mass Transfer

Each section contains maximum 80 Questions. To practice more questions visit other sections.

Heat and Mass Transfer, RAC  MCQ – Section-1

Heat and Mass Transfer, RAC  MCQ – Section-2

Heat and Mass Transfer, RAC  MCQ – Section-3

Heat and Mass Transfer, RAC  MCQ – Section-4