0.45

0.55

0.40

0.75

A. 0.45

Directly proportional to the thermal conductivity

Inversely proportional to density of substance

Inversely proportional to specific heat

All of the above

Kirchoffs law

Stefan's law

Wien' law

Planck's law

Watt/cm² °K

Watt/cm4 °K

Watt²/cm °K⁴

Watt/cm² °K⁴

Thermometer

Thermistor

Thermocouple

None of these

Universal gas constant

Kinematic viscosity

Thermal conductivity

Planck's constant

Fourier equation

Stefan-Boltzmann equation

Newton Reichmann equation

Joseph-Stefan equation

20°C

40°C

60°C

66.7°C

0.1

0.3

0.7

1.7

0.45

0.55

0.40

0.75

Melting of ice

Boiler furnaces

Condensation of steam in condenser

None of these

High thickness of insulation

High vapour pressure

Less thermal conductivity insulator

A vapour seal

_{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}

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

Wien's law

Planck's law

Stefan's law

Fourier's law

One

Two

Three

Four

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

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

Thermal conductivity

Thermal diffusivity

Density

Dynamic viscosity

Free electrons

Atoms colliding frequency

Low density

Porous body

_{min}/U

_{min}

_{min}

_{min}

I.C. engine

Air preheaters

Heating of building in winter

None of the above

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

S.H/(S.H + L.H)

(S.H + L.H) /S.H

(L.H - S.H)/S.H

S.H/(L.H - S.H)

Electric heater

Steam condenser

Boiler

Refrigerator condenser coils

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

Thermal resistance

Thermal coefficient

Temperature gradient

Thermal conductivity

Parallel flow

Counter flow

Cross flow

All of these

25 mm

40 mm

160 mm

800 mm

Same

Higher

More or less same

Very much lower

Black radiation

Full radiation

Total radiation

All of these