 # E-PolyLearning

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 1. The diagram shows heat conduction through a plane wall. The surface temperature is 475 K and it radiates heat to the surroundings at 335 K. If thermal conductivity of the material is 12.5 W/m degree, find the temperature gradient. Let convective coefficient be 80 W/m² degree and radiation factor is 0.9 a. – 1052.4 degree celsius b. – 2052.4 degree celsius c. – 3052.4 degree celsius d. – 4052.4 degree celsius
 View Answer Report Discuss 50-50! Answer: (a).– 1052.4 degree celsius

 2. From the concept of kinetic theory, mean travel velocity of the gas molecules is prescribed by the relation (Where, G = Universal gas constant M = Molecular weight of the gas T = Absolute temperature) a. V = (3M/GT)⅟₂ b. V = (3GT/M)⅟₂ c. V = (6T/GM)⅟₂ d. V = (3GT/2M)⅟₂
 View Answer Report Discuss 50-50! Answer: (b).V = (3GT/M)⅟₂

 3. Low temperature insulation are used when the enclosure is at a temperature lower than the ambient temperature. Which one of the following is not a low temperature insulation? a. Asbestos b. Cork c. Cattle hair d. Slag wool
 View Answer Report Discuss 50-50! Answer: (a).Asbestos

 4. The value of Lorenz number in 10¯⁸ W ohms/K² is a. 2.02 b. 2.35 c. 2.56 d. 2.45
 View Answer Report Discuss 50-50! Answer: (d).2.45

 5. Consider the following parameters (i) Composition (ii) Density (iii) Porosity (iv) Structure Then, thermal conductivity of glass wool varies from sample to sample because of variation is a. 1 and 2 b. 1, 2, 3 and 4 c. 1 and 3 d. 1, 2 and 3
 View Answer Report Discuss 50-50! Answer: (b).1, 2, 3 and 4

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