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According to Stefan’s law, the total radiation from a black body per second per unit area is proportional to____________________?
Related MCQs
Depending on the radiating properties, a body will be black when__________?
The total emissivity power is .defined as the total amount of radiation emitted by a black body per unit__________?
40% of incident radiant energy on the surface of a thermally transparent body is reflected back. If the transmissivity of the body be 0.15, then the emissivity of surface is__________?
The emissive power of a body depends upon its__________?
The ratio of the energy absorbed by the body to total energy falling on it is called__________?
The amount of radiation mainly depends on__________?
Absorptivity of a body will be equal to its emissivity__________?
Depending on the radiating properties, body will be transparent when__________?
Two plates spaced 150 mm apart are maintained at 1000°C and 70°C. The heat transfer will take place mainly by __________?
In regenerator type heat exchanger, heat transfer takes place by__________?
If the temperature of a solid surface changes form 27°C to 627°C, then its emissive power changes in the ratio of__________?
A perfect black body is one which__________?
Planck’s law holds good for__________?
A grey body is one whose absorptivity __________?
The thermal diffusivities for gases are generally__________?
Thermal diffusivity of a substance is __________?
Stefan Boltzmann law is applicable for heat transfer by __________?
The unit of Stefan Boltzmann constant is __________?
Log mean temperature difference in case of counter flow compared to parallel flow will be__________?
According to Stefan-Boltzmann law, ideal radiators emit radiant energy at a rate proportional to__________?
In free con-vection heat transfer, Nusselt number is function of__________?
Which of the following property of air does not increase with rise in temperature __________?
The energy distribution of an ideal reflector at higher temperatures is largely in the range of __________?
The value of Prandtl number for air is about __________?
Total emissivity of polished silver compared to black body is__________?
The value of the wavelength for maximum emissive power is given by __________?
The unit of overall coefficient of heat transfer is__________?
All radiations in a black body are__________?
According to Kirchoff’s law, the ratio of emissive power to absorptivity for all bodies is equal to the emissive power of a __________?
Joule sec is the unit of__________?
The concept of overall coefficient of heat transfer is used in case of heat transfer by__________?
In counter flow heat exchangers__________?
Fourier’s law of heat conduction is valid for__________?
LMTD in case of counter flow heat exchanger as compared-to parallel flow heat exchanger is __________?
According of Kirchhoff’s law__________?
A steam pipe is to be insulated by two insulating materials put over each other . For best results__________?
In heat exchangers, degree of approach is defined as the difference between temperatures of__________?
A non-dimensional number generally associated with natural convection heat transfer is__________?
Emissivity of a white polished body in comparison to a black body is__________?
Two balls of same material and finish have their diameters in the ratio of 2 : 1 and both are heated to same temperature and allowed to cool by radiation. Rate of cooling by big ball as compared to smaller one will be in the ratio of__________?
Heat conducted througfi unit area and unit thick face per unit time when temperature difference between opposite faces is unity,is called__________?
A grey body is one whose absorptivity__________?
The rate of energy emission from unit surface area through unit solid angle, along a normal to the surface, is known as __________?
In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by__________?
Unit of thermal diffusivity is__________?
Film coefficient is defined as Inside diameter of tube__________?
Thermal conductivity of wood depends on__________?
Thermal diffusivity is __________?
Moisture would find its way into insulation by vapour pressure unless it is prevented by __________ ?
Heat transfer by radiation mainly depends upon__________?
Which of the following has maximum value of thermal conductivity__________?
According to Stefan’s law, the total radiation from a black body per second per unit area is proportional to____________________?
A. absolute temperature
B. T2
C. T5
D. t
E. l/T
Correct Answer:
t
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Last Updated:
January 24, 2019