Heat Transfer From Extended Surfaces MCQs

Welcome to our comprehensive collection of Multiple Choice Questions (MCQs) on Heat Transfer From Extended Surfaces, a fundamental topic in the field of Heat Transfer. Whether you're preparing for competitive exams, honing your problem-solving skills, or simply looking to enhance your abilities in this field, our Heat Transfer From Extended Surfaces MCQs are designed to help you grasp the core concepts and excel in solving problems.

In this section, you'll find a wide range of Heat Transfer From Extended Surfaces mcq questions that explore various aspects of Heat Transfer From Extended Surfaces problems. Each MCQ is crafted to challenge your understanding of Heat Transfer From Extended Surfaces principles, enabling you to refine your problem-solving techniques. Whether you're a student aiming to ace Heat Transfer tests, a job seeker preparing for interviews, or someone simply interested in sharpening their skills, our Heat Transfer From Extended Surfaces MCQs are your pathway to success in mastering this essential Heat Transfer topic.

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Heat Transfer From Extended Surfaces MCQs | Page 2 of 8

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Q11.
In heat dissipation from an infinitely long fin, the boundary conditions are

a.

t = t0 at x = infinity and t = ta at x = 0

b.

t = t0 at x = 0 and t = ta at x = infinity

c.

t = t0 at x = 0 and t = ta at x = 0

d.

t = t0 at x = infinity and t = ta at x = infinity

Discuss
Answer: (b).t = t0 at x = 0 and t = ta at x = infinity
Q12.
The temperature distribution in case of infinitely long fin is

a.

t – t a/t₀ – t a = mx

b.

t – t a/t₀ – t a = -mx

c.

t – t a/t₀ – t a = e-m x

d.

t – t a/t₀ – t a = log (m x)

Discuss
Answer: (c).t – t a/t₀ – t a = e-m x
Q13.
The rate of heat transfer in case of infinitely long fin is given by

a.

(h P k A)^1/2 (t₀ – t a)

b.

(h P A)^1/2 (t₀ – t a)

c.

(P k A)^1/2 (t₀ – t a)

d.

(h k A)^1/2 (t₀ – t a)

Discuss
Answer: (a).(h P k A)^1/2 (t₀ – t a)
Q14.
Let us say there are two rods having same dimensions, one made of brass (k = 85W/m K) and the other of copper (k = 375W/m K), having one of their ends inserted into a furnace. At a section 10.5 cm away from the furnace, the temperature of brass rod is 120 degree Celsius. Find the distance at which the same temperature would be reached in the copper rod? Both ends are exposed to the same environment

a.

12.54 cm

b.

45.87 cm

c.

12.34 cm

d.

22.05 cm

Discuss
Answer: (d).22.05 cm
Q15.
Three rods, one made of silver (l = 420W/m K), second made of aluminum (k = 210W/m K) and the third made of iron (k = 70W/m K) are coated with a uniform layer of wax all around. The rods are placed vertically in a boiling water bath with 250 mm length of each rod projecting outside. If all the rods are having following dimensions i.e. diameter = 15 mm and length = 300 mm and have identical surface coefficient 12.5W/ m² K, work out the ratio of lengths up to which wax will melt on each rod

a.

2.45:1:1.732

b.

1.732:1:2.45

c.

2.45:1.732:1

d.

1.732:1:2.45

Discuss
Answer: (c).2.45:1.732:1
Q16.
A rod of 10 mm square section and 160 mm length with thermal conductivity of 50W/m K protrudes from a furnace wall at 200 degree Celsius with convective coefficient 20 W/ square m K. Make calculations for the heat convective up to 80 mm length

a.

6.84W

b.

7.34W

c.

4.54W

d.

5.47W

Discuss
Answer: (a).6.84W
Q17.
A fin protrudes from a surface which is held at a temperature higher than that of its environment. The heat transferred away from the fin is

a.

Heat escaping from the tip of the fin

b.

Heat conducted along the fin length

c.

Convective heat transfer from the fin surface

d.

Sum of heat conducted along the fin length and that convected from the surface

Discuss
Answer: (c).Convective heat transfer from the fin surface
Q18.
The value of correction length for equilateral fin is

a.

L C = 2 L + a/4(3)^1/2

b.

L C = L + a/4(3)^1/2

c.

L C = 3 L + a/4(3)^1/2

d.

L C = 6 L + a/4(3)^1/2

Discuss
Answer: (b).L C = L + a/4(3)^1/2
Q19.
The parameter m = (h P/k A C)^1/2 has been stated to increase in a long fin. If all other parameters are constant, then

a.

Profile of temperature will remain the same

b.

Along the length temperature drop will be less

c.

The parameter influences the heat flow only

d.

The temperature drop along the length will be steeper

Discuss
Answer: (d).The temperature drop along the length will be steeper
Q20.
The relevant boundary conditions in case of heat dissipation from a fin insulated at the tip are

a.

t = t₀ at x = 0 and d t/d x = 0 at x = 0

b.

t = t₀ at x = 0 and d t/d x = 0 at x = 1

c.

t = t₀ at x = 1 and d t/d x = 0 at x = 1

d.

t = t₀ at x = infinity and d t/d x = 0 at x = infinity

Discuss
Answer: (b).t = t₀ at x = 0 and d t/d x = 0 at x = 1
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