Engineering :: Heat Transfer
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| 131. |
Which of the following material has highest value of thermal diffusivity? |
| A. |
Concrete |
B. |
Mineral wool |
| C. |
Wood |
D. |
Steel |
| E. |
Lead |
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Answer: Option E
Explanation:
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| 132. |
A device for transferring heat from one fluid to another is known as |
| A. |
Condenser |
B. |
Radiation |
| C. |
Heat exchanger |
D. |
Evaporator |
Answer: Option C
Explanation:
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| 133. |
Heat is transferred from an electric bulb mainly by |
| A. |
Conduction |
B. |
Convection |
| C. |
Convection and conduction |
D. |
Radiation |
| E. |
Conduction, convection and radiation. |
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Answer: Option D
Explanation:
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| 134. |
Which of the following method is used for finding the thermal conductivity of rubber? |
| A. |
Lec's disc method |
B. |
Searles method |
| C. |
Cylindrical shell method |
D. |
Laby and Hercus method |
| E. |
Any of the above |
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Answer: Option A
Explanation:
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| 135. |
Thermal conductivity of liquids can be determined by |
| A. |
Guarded plate method |
B. |
Searles method |
| C. |
Laby and Hercus method |
D. |
Any of the above |
| E. |
None of the above |
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Answer: Option A
Explanation:
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| 136. |
Thermal conductivity of water at 20?C is nearly |
Answer: Option D
Explanation:
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| 137. |
Thermal conductivity of air at room temperature in kcal/m-hr-?C is nearly |
Answer: Option E
Explanation:
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| 138. |
Thermal conductivity of glass wool depends on |
| A. |
Composition |
B. |
Density |
| C. |
Porosity |
D. |
Structure |
| E. |
All of the above |
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Answer: Option E
Explanation:
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| 139. |
Insulation in cavity walls is |
| A. |
Water |
B. |
Air |
| C. |
Cork |
D. |
Wood |
| E. |
None of the above |
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Answer: Option B
Explanation:
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| 140. |
All bodies above absolute zero temperature emit radiation". Above statement is based on |
| A. |
Prevost theory |
B. |
Planck's law |
| C. |
D'Alambert's rule |
D. |
Wein's law |
| E. |
Stefan law |
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Answer: Option A
Explanation:
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