Question 1

Which rays have the least wavelength?
A)Ultraviolet
B)Cosmic rays
C)Irifrared
D)X-rays
E)Radio

Accepted Answer

Cosmic rays have the least wavelength among the options provided. They consist of high-energy particles from outer space, which have much shorter wavelengths compared to ultraviolet, infrared, X-rays, and radio waves.

Question 2

Ditus Boelter equation is applicable in case of fluids flowing in
A)Laminar region
B)Turbulent region
C)Transition region
D)Any of the above
E)None of the above

Accepted Answer

The Dittus-Boelter equation is specifically applicable for calculating the convective heat transfer coefficient in cases where fluids are flowing in the turbulent region. It is not accurate for laminar or transition flow conditions.

Question 3

Transmission of heat by molecular collision is
A)Scattering
B)Transmission
C)Radiation
D)Convection
E)Conduction

Accepted Answer

D

Question 4

The emissive power of a body depends on
A)Nature of body
B)Temperature of body
C)Physical nature
D)All of the above
E)None of the above

Accepted Answer

The emissive power of a body depends on the nature of the body, its temperature, and its physical nature, encompassing factors like surface texture and material composition.

Question 5

Floating heads are provided in heat exchangers to
A)Facilitate maintenance
B)Regulate the flow
C)Increase the pressure drop
D)Avoid deformation of tubes due to thermal expansion
E)Reduce the pressure drop

Accepted Answer

Floating heads are provided in heat exchangers to avoid deformation of tubes due to thermal expansion.

Question 6

The transfer of heat in case of radiation takes place by means of
A)Heated particles of the medium
B)Electromagnetic waves
C)Thermal energy of the source
D)None of the above
E)37,500 kg

Accepted Answer

The answer of The transfer of heat in case of...

Question 7

In case of liquids and gases, the heat transfer takes place according to
A)radiation
B)conduction
C)convection
D)Both (A) and (C)
E)Nichrome

Accepted Answer

In liquids and gases, heat transfer primarily occurs through convection, which involves the movement of fluid particles carrying heat.

Question 8

Which of the following has the highest value of the thermal conductivity
A)Wood
B)Asbestos
C)Nichrome
D)Clay
E)Refractory brick

Accepted Answer

Nichrome, a nickel-chromium alloy, has a higher thermal conductivity compared to wood, asbestos, clay, and refractory brick, making it more efficient in conducting heat.

Question 9

Which of the following is wrong
A)Black surfaces are better absorbers than white ones
B)Black surfaces are better radiators than white ones
C)Rough surfaces are better radiators than smooth surfaces
D)37,500 kg
E)Highly polished mirror like surfaces are very good radiators

Accepted Answer

Highly polished, mirror-like surfaces are poor radiators of heat. They reflect most of the heat radiation that falls on them, making them inefficient at radiating heat away.

Question 10

Which of the following are generally diathermanous?
A)Solids
B)Liquids
C)Gases
D)All of the above
E)37,500 kg

Accepted Answer

Gases are generally diathermanous because they allow the passage of heat without absorbing much of it, unlike most solids and liquids which tend to absorb heat.

Question 11

Longest wavelength
A)Ultraviolet rays
B)Infrared rays
C)Gamma rays
D)X-rays
E)Radio waves

Accepted Answer

The answer of Longest wavelength
A)Ultraviolet rays
B)Infrared rays
C)Gamma rays
D)X-rays
E)Radio waves...

Question 12

All bodies above absolute zero temperature emit radiation". Above statement is based on
A)D'Alambert's rule
B)Wein's law
C)Stefan law
D)Planck's law
E)Prevost theory

Accepted Answer

The statement is based on Prevost's theory of heat exchange, which states that all bodies emit radiation as long as they are above absolute zero temperature.

Question 13

Which one of the following will radiate heat to a large extent?
A)White polished surface
B)White rough surface
C)Black rough surface
D)Black polished surface
E)None of the above

Accepted Answer

The answer of Which one of the following will radiate...

Question 14

In a cooling tower which mode of heat transfer plays insignificant role?
A)Evaporative cooling
B)Convective cooling
C)Radiaion
D)All of the above
E)37,500 kg

Accepted Answer

Radiation plays an insignificant role in the operation of a cooling tower compared to evaporative and convective cooling mechanisms. Cooling towers primarily rely on the evaporation of water to remove heat from a system, with convective heat transfer also playing a significant role in the process. Radiation, on the other hand, is much less significant in this context.

Question 15

A dimensionless number which is the ratio of kinematic viscosity to thermal diffusivity is known as
A)Grashoff number
B)Reynolds number
C)Prandtl number
D)Pacelet number
E)Nusselt number

Accepted Answer

The Prandtl number is a dimensionless number, defined as the ratio of kinematic viscosity to thermal diffusivity. It is used in heat transfer and fluid flow problems.

Question 16

There metal walls of same cross-sectional area having thermal conductivity in the ratio 1 : 2 : 4 transfer heat at the rate of 15000 kcal/hr. For same thickness of wall, the temperature deop will be in the ratio
A)1 ; 2 ; 4
B)1 :
C)4 ; 2 ; 1
D)1 ; 1 ; 1

Accepted Answer

The answer of There metal walls of same cross-sectional area...

Question 17

Formation of fog is due to
A)High pressure
B)Humidity
C)Temperature fall of atmosphere
D)Low pressure
E)Night showers

Accepted Answer

The answer of Formation of fog is due to
A)High pressure
B)Humidity
C)Temperature...

Question 18

The radiation from flames consists of
A)Continuous radiation from burning soot particles of microscopic and submicroscopic dimensions
B)Radiation from suspended larger particles of coal, coke or ash contributing to flame luminosity
C)Infrared radiation from water vapour and carboundioxide
D)Non-equilibrium radiation associated with the combustion process
E)All of the above

Accepted Answer

The radiation from flames includes continuous radiation from burning soot particles, radiation from larger particles contributing to luminosity, infrared radiation from water vapor and carbon dioxide, and non-equilibrium radiation associated with combustion. These components together contribute to the complex radiation observed in flames.

Question 19

In a shell and tube heat exchanger, the corrosive liquid is normally passed through
A)Shell side.
B)Tube side
C)Either of (A) and (B) above
D)None of the above
E)None of the above.

Accepted Answer

In a shell and tube heat exchanger, the corrosive liquid is normally passed through the tube side because it is easier to replace or repair the tubes compared to the shell. Additionally, using smaller diameter tubes allows for the use of higher-grade, corrosion-resistant materials more economically.

Question 20

DBA = DAB, in case of A)Stagnet diffusion B)Equimolar counter diffusion C)Either of (A) and (B) above D)None of the above E)2.6 cm²/sec

Accepted Answer

In equimolar counter diffusion, the diffusion coefficients of the two species are equal, hence DBA = DAB.

Quiz 14: Components of Radiation From Flames

Which rays have the least wavelength?

Ditus Boelter equation is applicable in case of fluids flowing in

Transmission of heat by molecular collision is

The emissive power of a body depends on

Floating heads are provided in heat exchangers to

The transfer of heat in case of radiation takes place by means of

In case of liquids and gases, the heat transfer takes place according to

Which of the following has the highest value of the thermal conductivity

Which of the following is wrong

Which of the following are generally diathermanous?

Longest wavelength

All bodies above absolute zero temperature emit radiation". Above statement is based on

Which one of the following will radiate heat to a large extent?

In a cooling tower which mode of heat transfer plays insignificant role?

A dimensionless number which is the ratio of kinematic viscosity to thermal diffusivity is known as

There metal walls of same cross-sectional area having thermal conductivity in the ratio 1 : 2 : 4 transfer heat at the rate of 15000 kcal/hr. For same thickness of wall, the temperature deop will be in the ratio

Formation of fog is due to

The radiation from flames consists of

In a shell and tube heat exchanger, the corrosive liquid is normally passed through

DBA = DAB, in case of