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 9 of 21

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Q81.
The emissivity and the absorptivity of a real surface are equal for radiation with identical temperature and wavelength. This law is referred to as

a.

Kirchhoff’s law

b.

Lambert’s law

c.

Planck’s law

d.

Wein’s displacement law

Discuss
Answer: (a).Kirchhoff’s law
Q82.
With an increase in wavelength, the monochromatic emissive power of a black body

a.

Increases

b.

Decreases

c.

Decreases, reaches a minimum and then increases

d.

Increases, reaches a maximum and then decreases

Discuss
Answer: (d).Increases, reaches a maximum and then decreases
Q83.
The temperature of a solid surface changes from 27 K to 627 K. The emissive power changes would then confirm to the ratio

a.

6:1

b.

9:1

c.

81:1

d.

27:1

Discuss
Answer: (c).81:1
Q84.
If the temperature of a hot body is increased by 50%, the amount of radiations emitted by it would increase by nearly

a.

200%

b.

500%

c.

50%

d.

100%

Discuss
Answer: (b).500%
Q85.
Consider two bodies, one absolutely back and the other non-black and let these be at same temperature. Which one of the following statement is correct?

a.

Black body radiates less intensively than a non-black body

b.

Non-black body radiates less intensively than a black body

c.

Both will radiates equally

d.

None of them will radiates

Discuss
Answer: (b).Non-black body radiates less intensively than a black body
Q86.
When Stefan-Boltzmann law is applied to a black body, it takes the form

a.

E = σ T

b.

E = σ T²

c.

E = σ T³

d.

E = σ T⁴

Discuss
Answer: (d).E = σ T⁴
Q87.
When the emissivity of non-black surface is constant at all temperatures and throughout the entire range of wavelength, the surface is called

a.

Gray body

b.

Transparent body

c.

Opaque bodies

d.

Perfect black body

Discuss
Answer: (a).Gray body
Q88.
The emissivity of the gray surface may be expressed as

a.

σ /2 σb

b.

σ / 3 σb

c.

σ / σb

d.

½ σ / σb

Discuss
Answer: (c).σ / σb
Q89.
If a black body at 1000 K and a gray body at 1250 K emit the same amount of radiation, what should be the emissivity of the gray body?

a.

0.3096

b.

0.4096

c.

0.5096

d.

0.6096

Discuss
Answer: (b).0.4096
Q90.
The radiant heat transfer from a plate of 2.5 cm² area at 1250 K to a very cold enclosure is 5.0 W. Determine the emissivity of the plate at this temperature

a.

0.444

b.

0.344

c.

0.244

d.

0.144

Discuss
Answer: (d).0.144
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