Access and Discuss Multiple choice questions for various competitive Exams and Interviews.

1. Consider system A at uniform temperature t and system B at another uniform temperature T (t > T). Let the two systems be brought into contact and be thermally insulated from their surroundings but not from each other. Energy will flow from system A to system B because of
a. Temperature difference
b. Energy difference
c. Mass difference
d. Volumetric difference
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Answer: (a).Temperature difference

2. The literature of heat transfer generally recognizes distinct modes of heat transfer. How many modes are there?
a. One
b. Two
c. Three
d. Four
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Answer: (c).Three

3. An oil cooler in a high performance engine has an outside surface area 0.12 m² and a surface temperature of 65 degree Celsius. At any intermediate time air moves over the surface of the cooler at a temperature of 30 degree Celsius and gives rise to a surface coefficient equal to 45.4 W/ m² K. Find out the heat transfer rate?
a. 238.43 W
b. 190.68 W
c. 543.67 W
d. 675.98 W
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Answer: (b).190.68 W

4. Unit of rate of heat transfer is
a. Joule
b. Newton
c. Pascal
d. Watt
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Answer: (d).Watt

5. Convective heat transfer coefficient doesn’t depend on
a. Surface area
b. Space
c. Time
d. Orientation of solid surface
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Answer: (a).Surface area

6. The rate equation used to describe the mechanism of convection is called Newton’s law of cooling. So rate of heat flow by convection doesn’t depend on
a. Convective heat transfer coefficient
b. Surface area through which heat flows
c. Time
d. Temperature potential difference
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Answer: (c).Time

7. How many types of convection process are there?
a. One
b. Three
c. Four
d. Two
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Answer: (b).Three

8. Thermal conductivity is maximum for which substance
a. Silver
b. Ice
c. Aluminum
d. Diamond
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Answer: (d).Diamond

9. A radiator in a domestic heating system operates at a surface temperature of 60 degree Celsius. Calculate the heat flux at the surface of the radiator if it behaves as a black body
a. 697.2 W/m²
b. 786.9 W/m²
c. 324.7 W/m²
d. 592.1 W/m²
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Answer: (a).697.2 W/m²

10. Which of the following is an example of forced convection?
a. Chilling effect of cold wind on a warm body
b. Flow of water in condenser tubes
c. Cooling of billets in the atmosphere
d. Heat exchange on cold and warm pipes
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Answer: (b).Flow of water in condenser tubes

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