# Previous Years GATE Questions on Radiation

## Solved GATE Questions on Radiation

(A) 0.17

(B) 0.21

(C) 0.79

(D) 0.83

GATE-ME-2001

Hint 1. (Ans D)

(A) 0.83

(B) 1.17

(C) 0.66

(D) 1.34

GATE-ME-2002

Hint 2. (Ans A)

### Question 3. A plate having 10  area each side is hanging in the middle of a room of 100  total surface area. The plate temperature and emissivity are respectively 800 K and 0.6. The temperature and emissivity values for the surfaces of the room are 300 K and 0.3 respectively. Boltzmann’s constant . The total heat loss from the two surfaces of the plate is

(A) 13.66 W

(B) 27.32 W

(C) 27.87 W

(D) 13.66 MW

GATE-ME-2003

Hint 3. (Ans B)

Heat loss from one surface of the plate,

Putting

Heat loss from both the surfaces =2

(A) 8.33

(B) 16.66

(C) 39.68

(D) 79.36

GATE-ME-2004

Hint 1. (Ans B)

### The radiation configuration factor  is

(A) 0.375

(B) 0.625

(C) 0.75

(D) 1

GATE-ME-2005

Hint 5. (Ans C)

Since, , therefore

Now,

Now,

### The conclusion is that the measurements are

(A) Correct because the maxima in  show the correct trend.

(B) Correct because Planck’s law is satisfied.

(C) Wrong because the Stefan Boltzman law is not satisfied.

(D) Wrong because Wien’s displacement law is not satisfied

GATE-ME-2005

Hint 6. (Ans D)

When displacement law is not satisfied, i.e.,

Which tells lower  for higher temperatures.

### Question 7. A hollow enclosure is formed between two infinitely long concentric cylinders of radii 1m and 2m, respectively. Radiative heat exchange takes place between the inner surface of the larger cylinder (surface-2) and the outer surface of the smaller cylinder (surface-1). The radiating surfaces are diffuse and the medium in the enclosure is non-participating. The fraction of the thermal radiation leaving the larger surface and striking itself is

(A) 0.25

(B) 0.5

(C) 0.75

(D) 1

GATE-ME-2008

Hint 7. (Ans B)

due to concave surface

Now,

Common data  Question 8 and 9

Radiative  heat transfer is intended between the inner surfaces of two very small isothermal parallel metal plates. While the upper plate (designated as plate 1) is a black surface and the warmer on being maintained at 727, the lower plate (plate 2) is a diffuse and gray surface with an emissivity of 0.7 and is kept at 227 . Assume that the surface are sufficiently large to form surface enclosure and steady state conditions to exist. Stefan Boltzmann constant is given as 5.67.

(A) 2.5

(B) 3.6

(C) 17.0

(D) 19.5

GATE-ME-2009

Hint 8. (Ans A)

### Question 9. If plate 1 is also a diffuse and gray surface with an emissivity value of 0.8, the net radiation heat exchange () between plate 1 and plate 2 is

(A) 17.0

(B) 19.5

(C) 23.0

(D) 31.7

GATE-ME-2009

Hint 9. (Ans D)

Net heat exchange between A and B

(A)

(B)

(C)

(D)

GATE-ME-2012

Hint 10. (Ans C)

(A) 0.66

(B) 0.79

(C) 0.99

(D) 3.96

GATE-ME-2013

Hint 11. (Ans A)