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1. In case of heat conduction through plane wall, which one of the following is not a correct assumption?
a. Steady state
b. Three dimensional heat flow
c. Volumetric heat generation must be constant
d. K must be constant
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Answer: (b).Three dimensional heat flow

2. If Q X is heat generated in at distance ‘x’, then heat conducted out at a distance (x + d x) will be
a. Q X + 3d (Q X) d x /d x
b. 2Q X + d (Q X) d x /d x
c. d (Q X) d x /d x
d. Q X + d (Q X) d x /d x
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Answer: (d).Q X + d (Q X) d x /d x

3. Notable example of uniform generation of heat within the conducting medium are

(i) Energy of a nuclear reactor

(ii) Liberation of energy due to some exothermic chemical reactions

(iii) Resistance heating in electrical appliances

Which of the statements made above are correct?
a. 1, 2 and 3
b. 1 and 2
c. 1 and 3
d. Only 2
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Answer: (a).1, 2 and 3

4. For a plane wall of thickness l with uniformly distributed heat generation q g per unit volume, the temperature t₀ at mid plane is given by
a. t₀ = q g l²/2k +t w
b. t₀ = q g l²/4k +t w
c. t₀ = q g l²/8k +t w
d. t₀ = q g l²/16k +t w
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Answer: (c).t₀ = q g l²/8k +t w

5. The temperature drop in a plane wall with uniformly distributed heat generation can be decreased by reducing
a. Wall thickness
b. Heat generation rate
c. Thermal conductivity
d. Surface area
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Answer: (a).Wall thickness

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