Heat Radiation MCQs

Welcome to our comprehensive collection of Multiple Choice Questions (MCQs) on Heat Radiation, 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 Radiation 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 Radiation mcq questions that explore various aspects of Heat Radiation problems. Each MCQ is crafted to challenge your understanding of Heat Radiation 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 Radiation MCQs are your pathway to success in mastering this essential Heat Transfer topic.

Note: Each of the following question comes with multiple answer choices. Select the most appropriate option and test your understanding of Heat Radiation. You can click on an option to test your knowledge before viewing the solution for a MCQ. Happy learning!

So, are you ready to put your Heat Radiation knowledge to the test? Let's get started with our carefully curated MCQs!

Heat Radiation MCQs | Page 5 of 21

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Q41.
Establish a relation for shape factor for a conical cavity with respect to itself of depth h and diameter d. The cavity is closed on its outer surface with a flat plate

a.

1 – d/ (4 h² + d)^1/2

b.

1 – d/ (4 h² + d ²)^1/2

c.

1 – d/ (4 h + d²)^1/2

d.

1 – d/ (h² + d²)^1/2

Discuss
Answer: (b).1 – d/ (4 h² + d ²)^1/2
Q42.
A polished metal pipe 5 cm outside diameter and 370 K temperature at the outer surface is exposed to ambient conditions at 295 K temperature. The emissivity of the surface is 0.2 and the convection coefficient of heat transfer is 11.35 W/m² degree. Calculate the overall coefficient of heat transfer by the combined mode of convection and radiation

a.

11.04 W/m² degree

b.

12.04 W/m² degree

c.

13.04 W/m² degree

d.

14.04 W/m² degree

Discuss
Answer: (c).13.04 W/m² degree
Q43.
Radiant energy with an intensity of 800 W/m² strikes a flat plate normally. The absorptivity is thrice the reflectivity and twice the transmissivity. Determine the rate of transmission

a.

155.47 W/m²

b.

145.47 W/m²

c.

135.47 W/m²

d.

125.47 W/m²

Discuss
Answer: (b).145.47 W/m²
Q44.
With respect to incident radiation, transmissivity varies with

a.

Time

b.

Temperature

c.

Surface area

d.

Wavelength

Discuss
Answer: (d).Wavelength
Q45.
A body through which all the incident radiations passes, is called

a.

Opaque body

b.

Black body

c.

Transparent body

d.

White body

Discuss
Answer: (c).Transparent body
Q46.
Reflectivity is defined as

a.

Fraction of total energy transmitted by the body

b.

Fraction of energy reflected by the body

c.

Fraction of total energy absorbed by the body

d.

Fraction of total energy absorbed and radiated by the body

Discuss
Answer: (b).Fraction of energy reflected by the body
Q47.
Of the radiant energy 350W/m² incident upon a surface 250W/m² is absorbed, 60W/m² is reflected and the remainder is transmitted through the surface. Workout the value for reflectivity for the surface material

a.

0.181

b.

0.171

c.

0.161

d.

0.151

Discuss
Answer: (b).0.171
Q48.
A thin metal plate of 4 cm diameter is suspended in atmospheric air whose temperature is 290 K. This plate attains a temperature of 295 K when one of its face receives radiant energy from a heat source at the rate of 2 W. If heat transfer coefficient on both surfaces of the plate is stated to be 87.5 W/m 2 K, workout the energy lost by reflection

a.

0.8 W

b.

0.3 W

c.

0.9 W

d.

0.10 W

Discuss
Answer: (c).0.9 W
Q49.
The value of reflectivity depends upon
(i) Body temperature

(ii) Wavelength of reflected radiation

(iii) Nature of surface of body

Identify the correct statement

a.

1 and 2

b.

2 and 3

c.

2 only

d.

1 and 3

Discuss
Answer: (d).1 and 3
Q50.
When a surface absorbs a certain fixed percentage of striking radiation the surface is called

a.

Grey body

b.

Black body

c.

White body

d.

Opaque body

Discuss
Answer: (a).Grey body
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