Test: Kirchoff’s Law - Mechanical Engineering MCQ

αE_B

2 αE_B

3 αE_B

4 αE_B

3 E – α E _B = 0

2 E – α E _B = 0

E – α E _B = 0

½ E – α E _B = 0

2

1

3

4

Shines as a result of incident radiation

Gets heated up a result of absorption of incident radiation

Allows all the incident radiation to pass through it

Partly absorbs and partly reflects the incident radiation

Snow is nearly black to thermal radiation

Absorption of radiation occurs in a very thin layer of material n ear the surface

Transmissivity varies with wavelength of incident radiation

Most of the engineering materials have rough surfaces, and these rough surfaces give regular (specular) reflections

Kirchhoff’s law

Lambert’s law

Planck’s law

Wein’s displacement law

Increases

Decreases

Decreases, reaches a minimum and then increases

Increases, reaches a maximum and then decreases

6:1

9:1

81:1

27:1

200%

500%

50%

100%

1 denotes the radiant energy E emitted by the non-black surface impinges on the black surface

1 denotes the radiant energy E emitted by the black surface impinges on the non-black surface

2 and 3 denotes the quantity α E _b

4 denotes the quantity (1 – α) E _b