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 3 of 21

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Q21.
The absorptivity of a surface depends upon

(i) Direction of reflected radiation
(ii) Temperature of the surface
(iii) Composition

Identify the correct statements

a.

1, 2 and 3

b.

1 and 3

c.

2 only

d.

2 and 3

Discuss
Answer: (d).2 and 3
Q22.
What is the absorptivity of gray body?

a.

Below unity

b.

Unity

c.

2

d.

2.5

Discuss
Answer: (a).Below unity
Q23.
A body that reflects all the incident thermal radiations is called a

a.

Opaque body

b.

Gases

c.

Black body

d.

Specular body

Discuss
Answer: (d).Specular body
Q24.
Energy strikes a vertical hemispherical plate with an intensity of 640 W/m². The absorptivity is thrice the transmissivity and twice the reflectivity. Determine the rate of absorption

a.

449.12 W/m²

b.

349.12 W/m²

c.

249.12 W/m²

d.

149.12 W/m²

Discuss
Answer: (b).349.12 W/m²
Q25.
Let 220 W/m² of radiant energy is absorbed by a convex surface, 90 W/m² is reflected and 40 W/m² is transmitted through it. What is the value of absorptivity?

a.

0.72

b.

0.62

c.

0.52

d.

0.42

Discuss
Answer: (b).0.62
Q26.
For a grey surface

a.

Reflectivity equals emissivity

b.

Emissivity equals transmissivity

c.

Absorptivity equals reflectivity

d.

Emissivity is constant

Discuss
Answer: (d).Emissivity is constant
Q27.
Which quantity can be neglected for gases?

a.

Transmissivity

b.

Reflectivity

c.

Absorptivity

d.

None can be neglected

Discuss
Answer: (b).Reflectivity
Q28.
Absorptivity of a body is equal to its emissivity

a.

Under thermal equilibrium conditions

b.

For a polished surface

c.

At one particular temperature

d.

At shorter wavelengths

Discuss
Answer: (a).Under thermal equilibrium conditions
Q29.
Electromagnetic waves strikes a hot body maintained at 900 degree Celsius which has a reflectivity of 0.66 and a transmissivity of 0.022. Let the absorbed flux be 60 W/m². Determine the rate of incident flux

a.

168.67 W/m²

b.

178.67 W/m²

c.

188.67 W/m²

d.

198.67 W/m²

Discuss
Answer: (c).188.67 W/m²
Q30.
Radiation heat transfer is characterized by

a.

Due to bulk fluid motion, there is transport of energy

b.

Thermal energy transfer as vibrational energy in the lattice structure of the material

c.

Movement of discrete packets of energy as electromagnetic waves

d.

There is circulation of fluid by buoyancy effects

Discuss
Answer: (c).Movement of discrete packets of energy as electromagnetic waves
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