1.
Heat transfer takes place as per
A
zeroth law of thermodynamics
B
first law of thermodynamic
C
second law of the thermodynamics
D
Kirchoffs law
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Heat transfer takes place as per
zeroth law of thermodynamics
first law of thermodynamic
second law of the thermodynamics
Kirchoffs law
Temperature of steam at around 540°C can be measured by
thermometer
radiatiouv pyrometer
thermistor
thermocouple
Which of the following property of air does not increase with rise in temperature
thermal conductivity
thermal diffusivity
density
dynamic viscosity
Metals are good conductors of heat because
their atoms collide frequently
their atoms-are relatively far apart
they contain free electrons
they have high density
Which of the following is expected to have highest thermal conductivity
steam
solid ice
melting ice
water
All radiations in a black body are
reflected
refracted
transmitted
absorbed
Thermal diffusivity of a substance is .
proportional of thermal conductivity
inversely proportional to k
proportional to (k)
inversely proportional to k2
Heat is closely related with
liquids
energy
temperature
entropy
The thermal diffusivities for solids are generally
less than those for gases
jess than those for liquids
more than those for liquids and gases
more or less same as for liquids and gases
Heat transfer by radiation mainly depends upon
its temperature
nature of the body
kind and extent of its surface
all of the above
Thermal conductivity of air with rise in temperature
increases
decreases
remains constant
may increase or decrease depending on temperature
Thermal conductivity of water in general with rise in temperature
increases
decreases
remains constant
may increase or decrease depending on temperature
Thermal conductivity of non-metallic amorphous solids with decrease in temperature
increases
decreases
remains constant
may increase or decrease depending on temperature
Thermal conductivity of solid metals with rise in temperature normally
increases
decreases
remains constant
may increase or decrease depending on temperature
The insulation ability of an insulator with the presence of moisture would
increase
decrease
remain unaffected
may increase/decrease depending on temperature and thickness of insulation
Which of the following is a case of steady state heat transfer
I.C. engine
air preheaters
heating of building in winter
none of the above.
Moisture would find its way into insulation by vapour pressure unless it is prevented by
high thickness of insulation
high vapour pressure
less thermal conductivity insulator
a vapour seal
Which of the following has least value of conductivity
glass
water
plastic
air.
Cork is a good insulator because it has
free electrons
atoms colliding frequency
low density
porous body
Pick up the wrong case. Heat flowing from one side to other depends directly on
time
thickness
temperature difference
face area