HMT CONTENT BEYOND SYLLABUS-GAS RADIATION

Consider a beam of monochromatic radiation at wavelength λ that enters a layer of absorbing gas. As the beam passes through the gas layer, its intensity

• a) Decreases
  

• 
  b) Increases
  

• 
  c) Become twice
  

• 
  d) Remains same

When a gas or vapor is in the process of oxidation and combustion, it is called as

• 
  a) Oxidation
  

• 
  
  b) Flame
  

• 
  c) Reduction
  

• 
  d) Combustion

The monochromatic absorption coefficient depends upon
(i) Temperature
(ii) Time
(iii) Pressure
(iv) Wavelength
Identify the correct option

• a) i, ii and iv
  

• 
  b) ii, iii and iv
  

• 
  c) i and ii
  

• 
  d) i, iii and iv

Consider a beam of monochromatic radiation at wavelength λ that enters a layer of absorbing gas. As the beam passes through the gas layer, its intensity is given by

• a) d I _{λ X} = – K _λ I _{λ X} d x
  

• 
  b) d I _{λ X} = – 2 K _λ I _{λ X} d x
  

• 
  c) d I _{λ X} = – 3 K _λ I _{λ X} d x
  

• 
  d) d I _{λ X} = – 4 K _λ I _{λ X} d x

Which of the following have a continuous spectrum?
a) Solids
b) Liquids
c) Gases
d) Solids and liquids

• a) Solids
  

• 
  b) Liquids
  

• 
  c) Gases
  

• 
  d) Solids and liquids

Which of the following is/are known as selective absorbers?
a) Solids
b) Liquids
c) Gases and vapors
d) Vapors

• a) Solids
  

• 
  b) Liquids
  

• 
  c) Gases and vapors
  

• 
  d) Vapors

Which layers participated in the process of thermal radiation through solids and liquids?
a) 1 micron to 1 mm thick
b) 2 micron to 2 mm thick
c) 1 micron to 0.5 mm thick
d) 2 micron to 4.57 mm thick

• a) 1 micron to 1 mm thick
  

• 
  b) 2 micron to 2 mm thick
  

• 
  c) 1 micron to 0.5 mm thick
  

• 
  d) 2 micron to 4.57 mm thick

Some of the gases have low emissive power and absorptivity. They are considered practically diathermanous. Which of the following option is true?

• 
  b) Helium
  

• 
  b) Helium
  

• 
  c) Carbon-dioxide
  

• 
  d) Methane

Consider an enclosure formed by three surfaces having the following values of shape factors, emissivities and temperatures

Surface 1 i.e. curved cylindrical has an emissivity 0.75 and temperature 800 K
Surface 2 i.e. closing disc has an emissivity 0.8 and temperature 700 K
Surface 3 i.e. closing disc has an emissivity 0.8 and temperature 700 K
The closing flat discs are 25 mm in diameter and they have interspacing distance equal to 100 mm. If the shape factor between these two identical discs is 0.05, calculate the net rate of radiant heat flow from the curve surface to each of the closing end surface

• a) 1.561 W
  

• 
  b) 2.561 W
  

• 
  c) 3.561 W
  

• 
  d) 4.561 W

The nature of the fluid flow is governed by the following parameters
(i) Mean flow velocity
(ii) Density of fluid
(iii) Dynamic viscosity of the fluid
Identify the correct statements
a) i and iii
b) i only
c) i, ii and iii
d) ii and iii

• a) i and iii
  

• 
  b) i only
  

• 
  c) i, ii and iii
  

• 
  d) ii and iii