Conduction With Heat Generation(Heat Transfer ) Questions and answers for exam Preparation

Question 1. In case of heat conduction through plane wall, which one of the following is not a correct assumption?

Steady state
Three dimensional heat flow
Volumetric heat generation must be constant
K must be constant

Explanation:-

Answer: Option B. -> Three dimensional heat flow
Answer: (b).Three dimensional heat flow

Question 2. 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

t₀ = q g l²/2k +t w
t₀ = q g l²/4k +t w
t₀ = q g l²/8k +t w
t₀ = q g l²/16k +t w

Explanation:-

Answer: Option C. -> t₀ = q g l²/8k +t w
Answer: (c).t₀ = q g l²/8k +t w

Question 3. If Q X is heat generated in at distance ‘x’, then heat conducted out at a distance (x + d x) will be

Q X + 3d (Q X) d x /d x
2Q X + d (Q X) d x /d x
d (Q X) d x /d x
Q X + d (Q X) d x /d x

Explanation:-

Answer: Option D. -> Q X + d (Q X) d x /d x
Answer: (d).Q X + d (Q X) d x /d x

Question 4. The temperature drop in a plane wall with uniformly distributed heat generation can be decreased by reducing

Wall thickness
Heat generation rate
Thermal conductivity
Surface area

Explanation:-

Answer: Option A. -> Wall thickness
Answer: (a).Wall thickness

Question 5. 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?

1, 2 and 3
1 and 2
1 and 3
Only 2

Explanation:-

Answer: Option A. -> 1, 2 and 3
Answer: (a).1, 2 and 3

Question 6. Consider a slab of thickness δ with one side (x = 0) insulated and other side (x = δ) maintained at constant temperature. The rate of uniform heat generation within the slab is q g W/m³. Presuming that the heat conduction is in steady state and one dimensional along x direction, the maximum temperature in the slab would occur at x equal

δ/2
Zero
δ/4
δ

Explanation:-

Answer: Option B. -> Zero
Answer: (b).Zero

Question 7. In case when both the surfaces of plane wall are at different temperature, we get an expression i.e.
T MAX – T W2 /T W1 – TW2 = (B + 1)²/4B
What is the value of B?

(q g) (δ)²/2k (T W1 – TW2)
(q g) (δ)³/3k (T W1 – TW2)
(q g) (δ)⁴/4k (T W1 – TW2)
(q g) (δ)⁵/5k (T W1 – TW2)

Explanation:-

Answer: Option A. -> (q g) (δ)²/2k (T W1 – TW2)
Answer: (a).(q g) (δ)²/2k (T W1 – TW2)

Question 8. Which one of the following materials are quickly heated by applying high frequency?

Textiles
Engines
Rubber
Coal

Explanation:-

Answer: Option A. -> Textiles
Answer: (a).Textiles

Question 9. Suppose heat is conducted due to electrons
Where, i = I/A and p is the resistivity, then

q g = 2i² p
q g = 3i² p
q g = i² p
q g = 4i² p

Explanation:-

Answer: Option C. -> q g = i² p
Answer: (c).q g = i² p

Question 10. There occurs heat conduction and internal heat generation at uniform rate within the conduction medium itself in the following cases
(i) Drying of concrete
(ii) Chemical processes
(iii) Fuel elements in a nuclear reaction
Choose the correct option

1 only
2 only
1 and 3
1, 2 and 3

Explanation:-

Answer: Option D. -> 1, 2 and 3
Answer: (d).1, 2 and 3