P = 0, x = 0 and a = 1
P=1, x = 0, and a = 0
P = 0, T= 1, and a = 0
X = 0, a + p = 1
C. P = 0, T= 1, and a = 0
One
Two
Three
Four
Fourier equation
Stefan-Boltzmann equation
Newton Reichmann equation
Joseph-Stefan equation
Absorptive power
Emissive power
Emissivity
None of these
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.
Different heat contents
Different specific heat
Different atomic structure
Different temperatures
RN = hl/k
RN = μ cp/k
RN = ρ V l /μ
RN = V²/t.cp
Nature of the body
Temperature of the body
Type of surface of the body
All of these
Change vapour into liquid
Change liquid into vapour
Increase the temperature of a liquid of vapour
Convert water into steam and superheat it
Increases
Decreases
Remain constant
May increase or decrease depending on temperature
The heat transfer in liquid and gases takes place according to convection.
The amount of heat flow through a body is dependent upon the material of the body.
The thermal conductivity of solid metals increases with rise in temperature
Logarithmic mean temperature difference is not equal to the arithmetic mean temperature difference.
Iron
Lead
Concrete
Wood
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 dimensionless parameter
Function of temperature
Used as mathematical model
A physical property of the material
Conduction
Convection
Radiation
None of these
Parallel flow
Counter flow
Cross flow
All of these
Q = 2πkr1 r2 (T1 - T2)/ (r2 - r1)
Q = 4πkr1 r2 (T1 - T2)/ (r2 - r1)
Q = 6πkr1 r2 (T1 - T2)/ (r2 - r1)
Q = 8πkr1 r2 (T1 - T2)/ (r2 - r1)
Cold body to hot body
Hot body to cold body
Smaller body to larger body
Larger body to smaller body
Pb = pa - pv
Pb = pa + pv
Pb = pa × pv
Pb = pa/pv
Conduction
Convection
Radiation
Conduction and convection
k/h₀
2k/h₀
h₀/k
h₀/2k
Is black in colour
Reflects all heat
Transmits all heat radiations
Absorbs heat radiations of all wave lengths falling on it
W/m²K
W/m²
W/mK
W/m
Conduction
Convection
Radiation
None of these
Same
More
Less
Depends on other factors
A grey body is one which absorbs all radiations incident on it.
At thermal equilibrium, the emissivity and absorptivity are same.
The energy absorbed by a body to the total energy falling on it, is called emissivity.
A perfect body is one which is black in colour.
Stanton number
Biot number
Peclet number
Grashoff number
In heat exchanger design as a safety factor
In case of Newtonian fluids
When a liquid exchanges heat with a gas
None of the above
More than those for liquids
Less than those for liquids
More than those for solids
Dependent on the viscosity
Emissivity
Transmissivity
Reflectivity
Intensity of radiation
Conduction
Convection
Radiation
Conduction and convection