Domestic refrigerators
Water coolers
Room air conditioners
All of these
A. Domestic refrigerators
The time taken to attain the final temperature to be measured
The time taken to attain 50% of the value of initial temperature difference
The time taken to attain 63.2% of the value of initial temperature difference
Determined by the time taken to reach 100°C from 0°C
Watt/cm² °K
Watt/cm4 °K
Watt²/cm °K⁴
Watt/cm² °K⁴
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.
6
9
27
81
h₁ + h₂ + h₃
(h₁.h₂.h₃)1/3
1/h₁ + 1/h₂ + 1/h₃
None of these
Radiant heat is proportional to fourth power of absolute temperature
Emissive power depends on temperature
Emissive power and absorptivity are constant for all bodies
Ratio of emissive power to absorptive power for all bodies is same and is equal to the emissive power of a perfectly black body.
RN = hl/k
RN = μ cp/k
RN = ρ V l /μ
RN = V²/t.cp
Thermometer
Thermistor
Thermocouple
None of these
Glass
Water
Plastic
Air
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)
Radiators in automobile
Condensers and boilers in steam plants
Condensers and evaporators in refrigeration and air conditioning units
All of the above
Conduction
Convection
Radiation
Conduction and radiation combined
Change vapour into liquid
Change liquid into vapour
Increase the temperature of a liquid of vapour
Convert water into steam and superheat it
Irregular surfaces
Nonuniform temperature surfaces
One dimensional cases only
Two dimensional cases only
Steam
Solid ice
Melting ice
Water
Watt/mK
Watt/m²K²
Watt/m²K4
Watt/mK²
Nature of body
Temperature of body
Type of surface of body
All of the above
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
Kirchoffs law
Stefan's law
Wien' law
Planck's law
Conduction
Convection
Radiation
None of these
1 : 1
2 : 1
1 : 2
4 : 1
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
Shorter wavelength
Longer wavelength
Remain same at all wavelengths
Wavelength has nothing to do with it
Maximum
Minimum
Zero
None of these
Move actually
Do not move actually
Affect the intervening medium
Does not affect the intervening medium
Face area
Time
Thickness
Temperature difference
Directly proportional to the thermal conductivity
Inversely proportional to density of substance
Inversely proportional to specific heat
All of the above
The better insulation must be put inside
The better insulation must be put outside
One could place either insulation on either side
One should take into account the steam temperature before deciding as to which insulation is put where
Conduction
Convection
Radiation
None of these
Varies with temperature
Varies with wavelength of the incident ray
Is equal to its emissivity
Does not vary with temperature and. wavelength of the incident ray