Description : What states that for any two bodies in thermal equilibrium, the ratios of emissive power to the absorptivity are equal? A. Kirchhoff’s radiation law B. Newton’s law of cooling C. Stefan-Boltzmann law D. Hess’s law
Last Answer : Kirchhoff’s radiation law
Description : In thermal radiation for a black body (where, ε is emissivity and α is absorptivity) (A) α = 1; ε ≠ 1 (B) α ≠ 1, ε = 1 (C) α ≠ 1, ε ≠ 1 (D) α = 1; ε = 1
Last Answer : (D) α = 1; ε = 1
Description : An idealized perfect absorber and perfect emitter of radiation. a. elastic material b. transponder material c. Teflon d. blackbody
Last Answer : blackbody
Description : What is the absorptivity of a black body? A. 0 B. 1 C. 0.5 D. 0.25
Last Answer : 1
Description : What is the emissivity of a black body? A. 0 B. 1 C. 0.5 D. 0.25
Description : The absorptivity of a body is equal to its emissivity (A) At a particular temperature (B) For circular bodies (C) Under thermal equilibrium (D) None of these
Last Answer : (C) Under thermal equilibrium
Description : Which of the following is the formula for thermal resistance? A. Thickness of material/ thermal conductivity of material B. 2(thickness of material)/thermal conductivity of material C. ... / 2(thermal conductivity of material) D. Thickness of material x thermal conductivity of material
Last Answer : Thickness of material/ thermal conductivity of material
Description : What is a measure of the ability of a material to conduct heat? A. Specific heat capacity B. Coefficient of thermal expansion C. Coefficient of thermal conductivity D. Thermal conductivity
Last Answer : Thermal conductivity
Description : Which of the following items is not a path function (a) heat (b) work (c) kinetic energy (d) vdp (e) thermal conductivity.
Last Answer : Answer : e
Description : The radiation emitted by a body as a result of its temperature. a. Blackbody Radiation b. Thermal Inversion c. Thermionic Inversion d. Thermal Radiation
Last Answer : Thermal Radiation
Description : The thermal radiation emitted by a blackbody heated to a given temperature. a. Gamma Radiation b. Black Body Radiation c. Electromagnetic Radiation d. Alpha Radiation
Last Answer : Black Body Radiation
Description : What is considered as a perfect absorber as well as a perfect emitter? A. Gray body B. Black body C. Real body D. White body
Last Answer : Black body
Description : What is used for predicting the behavior of non-ideal gases? a. Compressibility factor b. Expansivity factor c. Emissivity factor d. Van-d-whal’s factor
Last Answer : Compressibility factor
Description : Which is NOT a characteristic of emissivity? A. It is high with most nonmetals B. It is directly proportional to temperature C. It is independent with the surface condition of the material D. It is low with highly polished metals
Last Answer : It is independent with the surface condition of the material
Description : reduction in thermal resistance during heat transfer does not occur in the (A) Convection heat transfer by stirring the fluid and cleaning the heating surface (B) Conduction heat transfer by ... Radiation heat transfer by increasing the temperature and reducing the emissivity (D) None of these
Last Answer : Option C
Description : Thermal radiation is an electromagnetic radiation with wavelengths in _____ range. A. 1 to 100 µm B. 0.1 to 100 µm C. 0.1 to 10 µm D. 10 to 100 µm
Last Answer : 0.1 to 100 µm
Description : It is an energy flux, equal to the rate of energy flow per unit area per unit time across some surface. a. Irradiance b. Radiant Intensity c. Luminosity d. Brightness
Last Answer : Luminosity
Description : What refers to the transfer of energy between a solid surface and the adjacent fluid that is in motion? A. Conduction B. Convection C. Radiation D. Electrification
Last Answer : Convection
Description : What refers to the heating of the earth’s atmosphere not caused by direct sunlight but by infrared light radiated by the surface and absorbed mainly by atmospheric carbon dioxide? A. Greenhouse effect B. Global warming C. Thermal rise effect D. Ozone effect
Last Answer : Greenhouse effect
Description : The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium". This is __________ law. (A) Kirchoff’s (B) Planck's (C) Wien's displacement (D) Stefan-Boltzmann
Last Answer : (A) Kirchoff’s
Description : What is defined as the force per unit area? A. Pressure B. Energy C. Work D. Power
Last Answer : Pressure
Description : What is defined as the ratio of the net electrical power output to the rate of fuel energy input? A. Combustion efficiency B. Thermal efficiency C. Overall efficiency D. Furnace efficiency
Last Answer : Overall efficiency
Description : Pick out the correct statement. (A) Higher is the temperature of the radiating body, higher is the wavelength of radiation (B) Logarithmic mean area is used for calculating the heat flow rate ... ) Solid angle subtended by the finite surface at the radiating element is called the angle of incidence
Last Answer : (B) Logarithmic mean area is used for calculating the heat flow rate through a thick walled cylinder
Description : What is a body that emits a constant emissivity regardless of the wavelength? A. Gray body B. Black body C. Real body D. White body
Last Answer : Gray body
Description : The rate at which this is quantity passes through a fixed boundary per unit time a. Flux b. Existence c. Irradiance d. All of these
Last Answer : All of these
Description : 1 British thermal unit (BTU) is equivalent to how many joules? A. 1016 B. 1043 C. 1023 D. 1054
Last Answer : 1054
Description : In a furnace, the heat taken by the charge/stock and the heat lost to the furnace structure & flue gases depends on the (A) Rate of firing and emissivity of flame (B) Thermal conductivity of the charge & ... (C) Nature of process; whether batch, continuous or intermittent (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : For an ideal black body (A) Absorptivity = 1 (B) Reflectivity = 1 (C) Emissivity = 0 (D) Transmissivity = 1
Last Answer : (A) Absorptivity = 1
Description : It is the deposition of radiant energy as heat into an absorbing body. a. Radiation b. Ionization c. Convection d. Insolation
Last Answer : Insolation
Description : At same temperatures, the radiation emitted by all real surfaces is ______ the radiation emitted by a black body. A. Less than B. Greater than C. Equal to D. Either less than or greater than
Last Answer : Less than
Description : What states that if two bodies are in thermal equilibrium with a third body, they are also in equilibrium with each other? A. Zeroth law of thermodynamics B. First law of thermodynamics C. Second law of thermodynamics D. Third law of thermodynamics
Last Answer : Zeroth law of thermodynamics
Description : When two bodies are in thermal equilibrium with a third body, they are also in thermal equilibrium with each other. This statement is called A. Zeroth law of thermodynamics B. First law of thermodynamics C. Second law of thermodynamics D. Kelvin Planck’s law
Last Answer : A. Zeroth law of thermodynamics
Description : What is sometimes known as the “Fourth-power law”? A. Kirchhoff’s radiation law B. Newton’s law of cooling C. Stefan-Boltzmann law D. Hess’s law
Last Answer : Stefan-Boltzmann law
Description : Which of the following is used in thermal power plant? a. Brayton cycle b. Reversed carnot cycle c. Rankine cycle d. Otto cycle
Last Answer : Rankine cycle
Description : Thermal power plant works on (a) Carnot cycle (b) Joule cycle (d) Rankine cycle (d) Otto cycle (e) Brayton cycle.
Last Answer : Answer : c
Description : The heat per unit mass per degree change in temperature a. specific heat b. isometric c. conservation of energy d. none of the above
Last Answer : specific heat
Description : Mass (not weight) per unit volume a. Specific Weight b. Specific Volume c. Density d. None of the above
Last Answer : Density
Description : The force per unit length across such a line in the surface is called _________. a. force per length b. surface tension c. Pressure d. Density
Last Answer : surface tension
Description : The heat Q per unit mass per degree change in temperature that must be supplied or removed to change the temperature of a substance. a. Specific Heat Capacity b. Latent Heat c. Heat of Transformation d. Internal Heat
Last Answer : Specific Heat Capacity
Description : Extensive properties per unit mass are called _____. A. Specific properties B. Relative properties C. Unit properties D. Phase properties
Last Answer : Specific properties
Description : The pressure’of a gas in terms of its mean kinetic energy per unit volume E is equal to (a) E/3 (b) E/2 (c) 3E/4 (d)2E/3 (e) 5E/4.
Last Answer : Answer : d
Description : The unit of pressure in S.I. units is (a) kg/cm2 (b) mm of water column (c) pascal (d) dynes per square cm (e) bars
Description : The ratio of total radiating power to the absorptivity of the body depends upon the __________ as per Kirchoff’s law. (A) Wavelength of radiation (B) Nature of the body (C) Temperature of the body (D) None of these
Last Answer : (C) Temperature of the body
Description : Define the following terms : (i) absorptivity (ii) reflectivity (iii) transmissivity (iv) emissivity
Last Answer : Absorptivity: It is the fraction of total incident radiation which is absorbed by a body. Reflectivity: It is the fraction of total incident radiation which is reflected by a body. Transmissivity: It ... total emissive power of a body to emissive power of a black body at the same temperature.
Description : At Equilibrium, the radiation emitted must equal the radiation absorbed. a. Boyle’s Law b. Planck’s Law c. Kirchoff’s Law d. Joule’s Law
Last Answer : Kirchoff’s Law
Description : Utilizing the answer to the previous problem, estimate the overall or average increase in temperature ( ΔT) of the concrete roof from the energy absorbed from the sun during a12hour day. Assume that all of the radiation absorbed goes into ... °C b. 8.9°C c. 9.9°C d. 10.9°C formula: ΔQ = m c ΔT
Last Answer : 7.9 °C
Description : What device measures infrared radiation below? a. thermocouple b. thermopile c. thermodynamic device d. thermos
Last Answer : thermopile
Description : A process by which heat is transferred through a material without a bulk movement of the material. a. Convection b. Conduction c. Radiation d. Emission
Last Answer : Conduction
Description : A process in which heat energy is transferred by the flow of fluid. a. Convection b. Conduction c. Radiation d. Sublimation
Description : _________ is the transition of a given substance from the solid to the gas phase with no intermediate liquid stage. a. Convection b. Conduction c. Radiation d. Sublimation
Last Answer : Sublimation