Explore topic-wise MCQs in Heat Transfer.

This section includes 13 Mcqs, each offering curated multiple-choice questions to sharpen your Heat Transfer knowledge and support exam preparation. Choose a topic below to get started.

1.

A gray body (E = 0.8) emits the same amount of heat as a black body at 1075 K. Find out the required temperature of the gray body

A. 1146.72 K
B. 1136.72 K
C. 1126.72 K
D. 1116.72 K
Answer» C. 1126.72 K
Discussion
2.

For a hemisphere solid angle is measured as

A. Radian and its maximum value is π
B. Degree and its maximum value is 180 degree
C. Steradian and its maximum value is 2π
D. Steradian and its maximum value is π
Answer» E.
Discussion
3.

The monochromatic emissivity € of a diffuse surface at 1600 K varies with wavelength in the following manner€ = 0.4 for 0 < λ < 2 = 0.8 for 2 < λ < 5Determine the total emissivity

A. 0.5558
B. 0.5568
C. 0.5578
D. 0.5588
Answer» D. 0.5588
Discussion
4.

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
Answer» E.
Discussion
5.

FOR_A_HEMISPHERE_SOLID_ANGLE_IS_MEASURED_AS?$

A. Radian and its maximum value is π
B. Degree and its maximum value is 180 degree
C. Steradian and its maximum value is 2π
D. Steradian and its maximum value is π
Answer» E.
Discussion
6.

A_gray_body_(E_=_0.8)_emits_the_same_amount_of_heat_as_a_black_body_at_1075_K._Find_out_the_required_temperature_of_the_gray_body$

A. 1146.72 K
B. 1136.72 K
C. 1126.72 K
D. 1116.72 K
Answer» C. 1126.72 K
Discussion
7.

A 100 W light bulb has a tungsten filament (emissivity = 0.30) which is required to operate at 2780 K. If the bulb is completely evacuated, calculate the minimum surface area of the tungsten filament

A. 0.98 * 10 <sup>-4</sup> m<sup>2</sup>
B. 1.98 * 10 <sup>-4</sup> m<sup>2</sup>
C. 2.98 * 10 <sup>-4</sup> m<sup>2</sup>
D. 3.98 * 10 <sup>-4</sup> m<sup>2</sup>
Answer» B. 1.98 * 10 <sup>-4</sup> m<sup>2</sup>
Discussion
8.

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
Answer» E.
Discussion
9.

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
Answer» C. 0.5096
Discussion
10.

The emissivity of the gray surface may be expressed as

A. σ /2 σ <sub>b</sub>
B. σ / 3 σ <sub>b</sub>
C. σ / σ <sub>b</sub>
D. ½ σ / σ <sub>b</sub>
Answer» D. ¬¨¬®≈í¬© ‚âà√¨‚àö√¢ / ‚âà√¨‚àö√¢ <sub>b</sub>
Discussion
11.

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
Answer» B. Transparent body
Discussion
12.

When Stefan-Boltzmann law is applied to a black body, it takes the form

A. E = σ T
B. E = σ T <sup>2</sup>
C. E = σ T <sup>3</sup>
D. E = σ T <sup>4</sup>
Answer» E.
Discussion
13.

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
Answer» C. Both will radiates equally
Discussion