Sensible heat is the heat required to
Change vapour into liquid
Change liquid into vapour
Increase the temperature of a liquid of vapour
Convert water into steam and superheat it
Correct Answer :
C. Increase the temperature of a liquid of vapour
Related Questions
The amount of heat flow through a body by conduction is
Directly proportional to the surface area of the body
Directly proportional to the temperature difference on the two faces of the body
Dependent upon the material of the body
All of the above
Depending on the radiating properties, a body will be opaque when
P = 0, x = 0 and a = 1
P=1, x = 0 and a = 0
P = 0, x = 1 and a = 0
X = 0, a + p = 1 Where a = absorptivity, p = reflectivity, X = transmissivity.
Conduction is a process of heat transfer
From one particle of the body to another without the actual motion of the particles
From one particle of the body to another by the actual motion of the heated particles
From a hot body to a cold body, in a straight line, without affecting the intervening medium
None of the above
The total radiation from a black body per second per unit area is ________ fourth power of the absolute temperature. This statement is known as Stefan Boltzmann law.
Equal to
Directly proportional to
Inversely proportional to
None of these
Upto the critical radius of insulation,
Added insulation will increase heat loss
Added insulation will decrease heat loss
Convective heat loss will be less than conductive heat loss
Heat flux will decrease
The value of the wavelength for maximum emissive power is given by
Wien's law
Planck's law
Stefan's law
Fourier's law
Sensible heat is the heat required to
Change vapour into liquid
Change liquid into vapour
Increase the temperature of a liquid of vapour
Convert water into steam and superheat it
Heat is transferred by all three modes of transfer, viz. conduction, convection and radiation in
Electric heater
Steam condenser
Boiler
Refrigerator condenser coils
Depending on the radiating properties, a body will be black when
P = 0, x = 0 and a = 1
P= 1, T = 0 and a = 0
P = 0, x = 1 and a = 0
X = 0, a + p = 0 Where a = absorptivity, p = reflectivity, X = transmissivity.
The amount of radiation mainly depends upon the
Nature of the body
Temperature of the body
Type of surface of the body
All of these
The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles caused by some mechanical means, is known as
Conduction
Free convection
Forced convection
Radiation
Kirchhoff's law states that
The total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature
The wave length corresponding to the maximum energy is proportional to the absolute temperature
The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body
None of the above
According to Dalton's law of partial pressures, (where pb = Barometric pressure, pa = Partial pressure of dry air, and pv = Partial pressure of water vapour)
Pb = pa - pv
Pb = pa + pv
Pb = pa × pv
Pb = pa/pv
When heat is transferred from one particle of hot body to another by actual motion of the heated particles, it is referred to as heat transfer by
Conduction
Convection
Radiation
Conduction and convection
A grey body is one whose absorptivity
Varies with temperature
Varies with the wave length of incident ray
Varies with both
Does not vary with temperature and wave length of the incident ray
A non-dimensional number generally associated with natural convection heat transfer is
Grashoff number
Nusselt number
Weber number
Prandtl number
A cube at high temperature is immersed in a constant temperature bath. It loses heat from its top, bottom and side surfaces with heat transfer coefficients of h₁, h₂ and h₃ respectively. The average heat transfer coefficient for the cube is
h₁ + h₂ + h₃
(h₁.h₂.h₃)1/3
1/h₁ + 1/h₂ + 1/h₃
None of these
According to Stefan's law, the total radiation from a black body per second per unit area is proportional to
Absolute temperature
T²
T⁵
T
If the energy radiated per second per sq. cm. of the surface for wave lengths lying between λ, and λ + dλ is represented by (eλ.dλ), then eλ is called
Absorptive power
Emissive power
Emissivity
None of these
According to Kirchoff's law, the ratio of emissive power to absorptivity for all bodies is equal to the emissive power of a
Grey body
Brilliant white polished body
Red hot body
Black body
The ratio of Nusselt number and the product of Reynold's number and Prandtl number is equal to
Stanton number
Biot number
Peclet number
Grashoff number
Heat transfer in liquid and gases takes place by
Conduction
Convection
Radiation
Conduction and convection
The process of heat transfer from one particle of the body to another is called conduction, when the particles of the body
Move actually
Do not move actually
Affect the intervening medium
Does not affect the intervening medium
Heat transfer by radiation mainly depends upon
Its temperature
Nature of the body
Kind and extent of its surface
All of the above
Radiation is the process of heat transfer in which heat flows from a ________, in a straight line, without affecting the intervening medium.
Cold body to hot body
Hot body to cold body
Smaller body to larger body
Larger body to smaller body
The heat is transferred by conduction, convection and radiation in
Melting of ice
Boiler furnaces
Condensation of steam in condenser
None of these
Which of the following has least value of conductivity?
Glass
Water
Plastic
Air
The thickness of thermal and hydrodynamic boundary layer is equal if Prandtl number is
Equal to one
Greater than one
Less than one
Equal to Nusselt number
In regenerator type heat exchanger, heat transfer takes place by
Direct mixing of hot and cold fluids
A complete separation between hot and cold fluids
Flow of hot and cold fluids alternately over a surface
Generation of heat again and again
Two balls of same material and finish have their diameters in the ratio of 2: 1 and both are heated to same temperature and allowed to cool by radiation. Rate of cooling by big ball as compared to smaller one will be in the ratio of
1 : 1
2 : 1
1 : 2
4 : 1