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.

A. P = 0, x = 0 and a = 1

It is impossible to transfer heat from low temperature source to t high temperature source

Heat transfer by radiation requires no medium

All bodies above absolute zero emit radiation

Heat transfer in most of the cases takes place by combination of conduction, convection and radiation

Domestic refrigerators

Water coolers

Room air conditioners

All of these

Kirchoffs law

Stefan's law

Wien' law

Planck's law

Temperature

Wave length

Physical nature

All of the above

Face area

Time

Thickness

Temperature difference

Absolute temperature

T²

T⁵

T

20°C

40°C

60°C

66.7°C

Nature of the body

Temperature of the body

Type of surface of the body

All of these

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

Absolute temperature (T)

I²

F

T

h₁ + h₂ + h₃

(h₁.h₂.h₃)1/3

1/h₁ + 1/h₂ + 1/h₃

None 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

At all temperatures

At one particular temperature

When system is under thermal equilibrium

At critical temperature

Fourier equation

Stefan-Boltzmann equation

Newton Reichmann equation

Joseph-Stefan equation

Steam

Solid ice

Melting ice

Water

Solids

Liquids

Gases

None of these

Its temperature

Nature of the body

Kind and extent of its surface

All of the above

Absorptive power

Emissive power

Absorptivity

Emissivity

Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁)

Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)]

Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁)

Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁)

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.

Density

Coefficient of viscosity

Gravitational force

All of these

_{m} = (Δt_{1} - Δt_{2})/ log_{e} (Δt_{1}/Δt_{2})

_{m} = log_{e} (Δt_{1}/Δt_{2})/ (Δt_{1} - Δt_{2})

_{m} = t_{m} = (Δt_{1} - Δt_{2}) log_{e} (Δt_{1}/Δt_{2})

_{m} = log_{e} (Δt_{1} - Δt_{2})/ Δt_{1}/Δt_{2}

Irregular surfaces

Nonuniform temperature surfaces

One dimensional cases only

Two dimensional cases only

Kirchhoff's law

Stefan's law

Wines law

Planck's law

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

Absorptive power

Emissive power

Emissivity

None of these

Both the fluids at inlet (of heat exchanger where hot fluid enters) are in their coldest state

Both the fluids at inlet are in their hottest state

Both the fluids at exit are in their hottest state

One fluid is in hottest state and other in coldest state at inlet

Equal to

Directly proportional to

Inversely proportional to

None of these

Cold body to hot body

Hot body to cold body

Smaller body to larger body

Larger body to smaller body

Increases

Decreases

Remain constant

May increase or decrease depending on temperature