Multiple Choice Questions on Heat Transfer
1- The concept of overall coefficient of heat transfer is used in heat transfer problems of
(A) conduction
(B) convection
(C) radiation
(D) conduction and convection
2- According to Wien’s law, the wavelength corresponding to maximum energy is directly proportional to
(A) absolute temperature (T)
(B) T2
(C) T4
(D) 1/T
3- The transfer of heat by molecular collision is smallest in
(A) solids
(B) liquids
(C) gases
(D) none of the above
4- When absorptivity = 1, reflectivity = 0 and transmissivity = 0, then the body is said to be
(A) gray body
(B) white body
(C) opaque body
(D) black body
5- The thermal conductivity is expressed as
(A) W/m K
(B) W/m2 K
(C) W/hm K
(D) W/h2m2 K
6- The Fourier’s law of heat transfer by conduction is expressed as
(A) Q= kA2 dt/dx
(B) Q= kA dt/dx
(C) Q= k2A dx/dt
(D) Q= k3A dx/dt
7- Stefan-Boltzmann law is expressed as
(A) Q=σAT4
(B) Q=σA2T4
(C) Q=σAT2
(D) Q=σA2T4
8- Heat transmission is directly linked with the transport of medium itself, i.e., there is actual motion of heated particles during
(A) Conduction only
(B) Convection only
(C) Radiation only
(D) Conduction as well as radiation
9- Which of the following is anisotropic, i.e. ,exhibits change in thermal conductivity due to directional preferences
(A) Wood
(B) Glass wool
(C) Concrete
(D) Masonry brick
10- A satellite in space exchanges heat with the surroundings essentially by
(A) Conduction
(B) Convection
(C) Radiation
(D) Conduction and convection put together
ANSWERS:
1-(D), 2-(D), 3-(C), 4-(D), 5-(A), 6-(B), 7-(A), 8-(B), 9-(A), 10-(C)