A. the time taken to attain the final temperature to be measured
B. the time taken to attain 50% of the value of initial temperature difference
C. the time taken to attain 63.2% of the value of initial temperature difference
D. determined by the time taken to reach 100°C from 0°C
E. none of the above
Related Mcqs:
- The unit of Stefan Boltzmann constant is ____________________?
A. watt/cm2 °K
B. watt/cm4 °K
C. watt2/cm °K4
D. watt/cm2 °K4
E. watt/cm2 °K2 - The amount of heat flow through a body by conduction is_______________?
A. directly proportional to the surface area of the body
B. directly proportional to the temperature difference on the two faces of the body
C. dependent upon the material of the body
D. inversely proportional to the thickness of the body
E. all of the above - When heat is Transferred by molecular collision, it is referred to as heat transfer by __________________?
A. conduction
B. convection
C. radiation
D. scattering
E. convection and radiation - Thermal conductivity of water in general with rise in temperature ____________________?
A. increases
B. decreases
C. remains constant
D. may increase or decrease depending on temperature
E. none of the above - Total heat is the heat required to__________________?
A. change vapour into liquid
B. change liquid into vapour
C. increase the temperature of a liquid or vapour
D. convert water into steam and superheat it
E. convert saturated steam into dry steam - Which of the following has maximum value of thermal conductivity________________?
A. aluminium
B. steel
C. brass
D. copper
E. lead - A non-dimensional number generally associated with natural convection heat transfer is________________?
A. Grashoff number
B. Nusselt number
C. Weber number
D. Prandtl number
E. Reynold number - Fourier’s law of heat conduction is valid for_________________?
A. one dimensional cases only
B. two dimensional cases only
C. three dimensional cases only
D. regular surfaces having non-uniform temperature gradients
E. irregular surfaces - Log mean temperature difference in case of counter flow compared to parallel flow will be________________?
A. same
B. more
C. less
D. depends on other factors
E. none of the above - Depending on the radiating properties, a body will be black when_________________?
A. p = 0, x = 0 and a = 1
B. p= l,T = 0anda = 0
C. p = 0, x = 1 and a = 0
D. x = 0, a + p = 0
E. a = 0,x + p= 1.
where a = absorptivity, p == reflectivity, X = transmissivity
