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
C. The time taken to attain 63.2% of the value of initial temperature difference
Blast furnace
Heating of building
Cooling of parts in furnace
Heat received by a person from fireplace
Equal to
Directly proportional to
Inversely proportional to
None of these
Grey body
Brilliant white polished body
Red hot body
Black body
Black bodies
Polished bodies
All coloured bodies
All of the above
Universal gas constant
Kinematic viscosity
Thermal conductivity
Planck's constant
25 mm
40 mm
160 mm
800 mm
Free electrons
Atoms colliding frequency
Low density
Porous body
Conduction
Convection
Radiation
Conduction and convection
Conduction
Convection
Radiation
Conduction and convection
Remain same
Decreases
Increases
May increase or decrease depending upon temperature
A dimensionless parameter
Function of temperature
Used as mathematical model
A physical property of the material
Conduction
Free convection
Forced convection
Radiation
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
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
Steam
Solid ice
Melting ice
Water
Absolute temperature
T²
T⁵
T
Higher
Lower
Same
Depends on the area of heat exchanger
Nature of body
Temperature of body
Type of surface of body
All of the above
Melting of ice
Boiler furnaces
Condensation of steam in condenser
None of these
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
Thermal coefficient
Thermal resistance
Thermal conductivity
None of these
Directly proportional to the surface area
Directly proportional to the difference of temperatures between the two bodies
Either (A) or (B)
Both (A) and (B)
Same
More
Less
Depends on other factors
k. A. (dT/dx)
k. A. (dx/dT)
k. (dT/dx)
k. (dx/dT)
Thermal conductivity to the equivalent thickness of the film of fluid
Temperature drop through the films of fluids to the thickness of film of fluids
Thickness of film of fluid to the thermal conductivity
Thickness of film of fluid to the temperature drop through the films of fluids
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 = 1 Where a = absorptivity, p = reflectivity, x = transmissivity
Increase
Decrease
Remain unaffected
May increase/decrease depending on temperature and thickness of insulation
Change vapour into liquid
Change liquid into vapour
Increase the temperature of a liquid or vapour
Convert water into steam and superheat it
Cold body to hot body
Hot body to cold body
Smaller body to larger body
Larger body to smaller body
Quantity of heat flowing in one second through one cm cube of material when opposite faces ^re maintained at a temperature difference of 1°C
Quantity of heat flowing in one second through a slab of the material of area one cm square, thickness 1 cm when its faces differ in temperature by 1°C
Heat conducted in unit time across unit area through unit thickness when a temperature difference of unity is maintained between opposite faces
All of the above