Fourier's law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow, and k = Thermal conductivity of the body)
k. A. (dT/dx)
k. A. (dx/dT)
k. (dT/dx)
k. (dx/dT)
Correct Answer :
A. k. A. (dT/dx)
Related Questions
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Newton's law of cooling
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Stefan's law
Fourier's law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow, and k = Thermal conductivity of the body)
k. A. (dT/dx)
k. A. (dx/dT)
k. (dT/dx)
k. (dx/dT)
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Parallel flow
Counter flow
Cross flow
All of these
Thermal conductivity of water in general with rise in temperature
Increases
Decreases
Remain constant
May increase or decrease depending on temperature
The unit of Stefan Boltzmann constant is
Watt/cm² °K
Watt/cm4 °K
Watt²/cm °K⁴
Watt/cm² °K⁴
The amount of heat flow through a body by conduction is
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 diffusivity of a substance is given by (where h = Thermal diffusivity, ρ = Density of substance, S = Specific heat, and k = Thermal conductivity)
h = k/ ρS
h = ρS/k
h = S/ρk
h = kρ/S
Cork is a good insulator because it has
Free electrons
Atoms colliding frequency
Low density
Porous body
LMTD in case of counter flow heat exchanger as compared to parallel flow heat exchanger is
Higher
Lower
Same
Depends on the area of heat exchanger
Thermal diffusivity of a substance is
Directly proportional to the thermal conductivity
Inversely proportional to density of substance
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All of the above
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Kirchhoff's law
Stefan's law
Wines law
Planck's law
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Stefan-Boltzmann equation
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Joseph-Stefan equation
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Equal to one
Greater than one
Less than one
Equal to Nusselt number
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Same
More
Less
Depends on other factors
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Varies with temperature
Varies with the wave length of incident ray
Varies with both
Does not vary with temperature and wave length of the incident ray
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Conduction
Convection
Radiation
Conduction and convection
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Different specific heat
Different atomic structure
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I.C. engine
Air preheaters
Heating of building in winter
None of the above
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Radiation
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Pb = pa + pv
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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
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Decreases
Remain constant
May increase or decrease depending on temperature
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Absolute temperature
Square of the absolute temperature
Cube of the absolute temperature
Fourth power of the absolute temperature
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The wave length corresponding to the maximum energy is proportional to the absolute temperature
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None of the above