MCQs

Total Questions : 38 | Page 1 of 4 pages
Question 1. The famous Fourier series is named after
1.    Diller and Ryan
2.    J.B. Joseph Fourier
3.    Stefan- Boltzmann
4.    Wein’s
Answer: Option B. -> J.B. Joseph Fourier
Question 2. Fourier law of heat conduction is best represented by
1.    Q = -k A d t /d x
2.    Q = k A d x/d t
3.    Q = -k A
4.    Q = k d t/d x
Answer: Option A. -> Q = -k A d t /d x
Answer: (a).Q = -k A d t /d x
1.    Heat always flow is in the direction of positive temperature gradient
2.    Heat always flow in the direction of negative temperature gradient
3.    No heat flow is there
4.    Data is insufficient
Answer: Option B. -> Heat always flow in the direction of negative temperature gradient
Question 4. Consider the following statements:
The Fourier heat conduction equation
Q = -k A d t /d x
Presumes
ii) Constant value of thermal conductivity
iii) Uniform temperature at the wall surface
iv) One dimensional heat flow
Which of these statements are correct?
1.    1, 2 and 3
2.    1, 2 and 4
3.    2, 3 and 4
4.    1, 3 and 4
Answer: Option D. -> 1, 3 and 4
Question 5. Here are some assumptions that are made for Fourier law. Identify the wrong one
1.    No internal heat generation
3.    Non- linear temperature profile
4.    Isotropic and homogenous material
Answer: Option C. -> Non- linear temperature profile
Question 6. 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
1.    – 1052.4 degree celsius
2.    – 2052.4 degree celsius
3.    – 3052.4 degree celsius
4.    – 4052.4 degree celsius
Answer: Option A. -> – 1052.4 degree celsius
Question 7. 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)
1.    V = (3M/GT)⅟₂
2.    V = (3GT/M)⅟₂
3.    V = (6T/GM)⅟₂
4.    V = (3GT/2M)⅟₂
Answer: Option B. -> V = (3GT/M)⅟₂
Question 8. The value of Lorenz number in 10¯⁸ W ohms/K² is
1.    2.02
2.    2.35
3.    2.56
4.    2.45
Question 9. 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?
1.    Asbestos
2.    Cork
3.    Cattle hair
4.    Slag wool
Question 10. 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
1.    1 and 2
2.    1, 2, 3 and 4
3.    1 and 3
4.    1, 2 and 3
Answer: Option B. -> 1, 2, 3 and 4
Answer: (b).1, 2, 3 and 4