Move actually
Do not move actually
Affect the intervening medium
Does not affect the intervening medium
B. Do not move actually
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)
Conduction
Free convection
Forced convection
Radiation
Increase
Decrease
Remain unaffected
May increase/decrease depending on temperature and thickness of insulation
In conduction, reduction in the thickness of the material and an increase in thermal conductivity.
In convection, stirring of the fluid and cleaning the heating surface.
In radiation, increasing the temperature and reducing the emissivity.
All of the above
Their atoms collide frequently
Their atoms are relatively far apart
They contain free electrons
They have high density
Thermal conductivity
Thermal diffusivity
Density
Dynamic viscosity
High thickness of insulation
High vapour pressure
Less thermal conductivity insulator
A vapour seal
Zeroth law of thermodynamics
First law of thermodynamics
Second law of thermodynamics
Kirchhoff's law
Below which a gas does not obey gas laws
Above which a gas may explode
Below which a gas is always liquefied
Above which a gas will never liquefied
Less than those for gases
Less than those for liquids
More than those for liquids and gases
More or less same as for liquids and gases
Wien's law
Stefan's law
Kirchhoff's law
Planck's law
Increases
Decreases
Remain constant
May increase or decrease depending on temperature
S.H/(S.H + L.H)
(S.H + L.H) /S.H
(L.H - S.H)/S.H
S.H/(L.H - S.H)
Conduction
Convection
Radiation
Conduction and radiation combined
20°C
40°C
60°C
66.7°C
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
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.
Equivalent thickness of film
Thermal conductivity Equivalent thickness of film Specific heat × Viscosity
Thermal conductivity Molecular diffusivity of momentum Thermal diffusivity
Film coefficient × Inside diameter Thermal conductivity
I.C. engine
Air preheaters
Heating of building in winter
None of the above
h = k/ ρS
h = ρS/k
h = S/ρk
h = kρ/S
Its temperature
Nature of the body
Kind and extent of its surface
All of the above
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.
Aluminium
Steel
Brass
Copper
Emissivity
Transmissivity
Reflectivity
Intensity of radiation
Radiators in automobile
Condensers and boilers in steam plants
Condensers and evaporators in refrigeration and air conditioning units
All of the above
Absolute temperature (T)
I²
F
T
Convection
Radiation
Forced convection
Free convection
Reynold's number
Grashoff's number
Reynold's number, Grashoff's number
Prandtl number, Grashoff's number
One
Two
Three
Four
One dimensional cases only
Two dimensional cases only
Three dimensional cases only
Regular surfaces having non-uniform temperature gradients