# Mechanical Engineering Multiple choice Questions Answers # “HEAT TRANSFER”

### Mechanical Engineering MCQS

from FreePDfbook.com

1. Unit of thermal conductivity in M.K.S. units is
(a) kcal/kg m2 °C
(b) kcal-m/hr m2 °C
(c) kcal/hr m2 °C
(d) kcal-m/hr °C
(e) kcal-m/m2 °C.
Ans: b

2. Unit of thermal conductivity in S.I. units is
(a) J/m2 sec
(b) J/m °K sec
(c) W/m °K
(d) (a) and (c) above
(e) (b) and (c) above.
Ans: e

3. Thermal conductivity of solid metals with rise in temperature normally
(a) increases
(b) decreases
(c) remains constant
(d) may increase or decrease depending on temperature
(e) unpredictable.
Ans: b

4. Thermal conductivity of non-metallic amorphous solids with decrease in temperature
(a) increases
(b) decreases
(c) remains constant
(d) may increase or decrease depending on temperature
(e) unpredictable.
Ans: b

5. Heat transfer takes place as per –
(a) zeroth law of thermodynamics
(b) first law of thermodynamic
(c) second law of the thermodynamics
(d) Kirchoff’s law (e) Stefan’s law.
Ans: c

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120. 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.
Ans: d

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