The temperature of sun can be measured using a
A.standard thermometer
B.radiation pyrometer
C.platinum resistance thermometer
D.mercury thermometer
Category: Heat Transfer Mcqs
Which of the following material has highest value of thermal diffusivity?
A.Concrete
B.Mineral wool
C.Wood
D.Steel
E.Lead
The temperature reading taken using Centigrade and Fahrenheit thermometers are plotted on a graph -?C along X-axis, ?F along Y-axis. The shape of graph would be
A.Straight line cutting an intercept on the positive Y-axis
B.Straight line cutting an intercept on the positive X-axis
C.Straight line cutting an intercept on the negative Y-axis
D.Straight line cutting an intercept on the negative X-axis
In the temperature of air above a pond is 8?C thermal conductivity of ice is 0.005 C.G.S. units, latent heat of fusion of ice is 79.9 cal/gram the density of ice is 1 gm/cu.m, the time taken for the formation of ice layer of 1 cm thickness is
A.200 seconds
B.100 seconds
C.12.5 seconds
D.10 seconds
E.None of the above
A sphere of radius 40 cm is lagged to a radius of 50 cm. The temperatures of outer and inner surfaces are 66?C and 235?C respectively. Thermal conductivity of logging per cm thickness is 0.7 kcal/m-hr?C. The rate of heat leakage will be
A.1.49 kcal/hr
B.298 kcal/hr
C.398 kcal/hr
D.500 kcal/hr
E.666 kcal/hr
Baffles are provided in heat exchangers to
A.Remove dirt
B.Increase heat transfer rate
C.Provide better mechanical strength
D.Reduce heat transfer rate
E.Reduce vibrations
In a psychrometric chart the abscissa represents
A.Dry bulb temperature
B.Wet bulb temperature
C.Specific humidity
D.Relative humidity
E.Enthalpy
Which is the unit of Stefan Boltzmann constant
A.W/m2 K4
B.erg/cm2-sec-K4
C.cal/cm2-sec K4
D.kcal/m2-hr-K4
E.All of the above
Tea pots are highly polished
A.So that they may not conduct heat from outside
B.So that they may absorb all radiation from outside
C.To make them attractive to look at
D.Because porcelain takes high polish
E.None of the above
A dimensionless group which represents the rate of the (product of intertial forces times buoyant forces) to viscous force squared is known as
A.Reynolds number
B.Prandtl number
C.Nusselt number
D.Grashof number
E.Mach number
