11) The temperature distribution for a plane wall, for steady state heat flow and constant value of thermal conductivity is
a) logarithmic
b) parabolic
c) linear
d) exponential
12)Metals are good conductors of heat because
(a) their atoms collide frequently
(b) their atomsare relatively far apart
(c) they contain free electrons
(d) they have high density
(e) all of the above.
13) The critical thickness of insulation for cylinder is given by
a) K/h
b) 2K/h
c) h/K
d) 2h/K
14)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.
15) The effectiveness of a fin will be maximum in an environment with
a) free convection
b) forced convection
c) radiation
d) convection and radiation
16) Transient conduction means
a) very little heat transfer
b) heat transfer for a short time
c) heat transfer with a very small temperature difference
d) conduction when the temperature at a point varies with time
17) In a lumped parameter model, the temperature variation with time is
a) cubic
b) Linear
c) Exponential
d) Sinusodial
18) In convection heat transfer one of the significant dimensionless number is
a) Schmidt number
b) Nusselt number
c) Poisson number
d) Froude number
19) The Prandtl number will be lowest for
a) Water
b) Liquid metal
c) Aqueous solution
d) Lube oil
20) Which of the following dimensionless number/parameter is different from others ?
a) Eckert number
b) Colburn factor
c) Nusselt number
d) Stanton number