Heat Transfer MCQ’s – Steady and Unsteady Heat Transfer
1 - Question
Regarding one dimensional heat transfer, choose the correct statement.
a) Steady – f (x), Unsteady – f (x, t)<br/>
b) Steady – f (x, t), Unsteady – f (x)<br/>
c) Steady – f (x, y, t), Unsteady – f (x)<br/>
d) Steady – f (y, z), Unsteady – f (y)
View Answer
Answer: a<br/>
Explanation: In case of one dimensional heat flow steady state is a function of x coordinate only while unsteady state is a function of x coordinate and time only.
2 - Question
Which statement is true regarding steady state condition?
a) There is a variation in temperature in the course of time<br/>
b) Heat exchange is constant<br/>
c) It is a function of space and time coordinates<br/>
d) Internal energy of the system changes
View Answer
Answer: b<br/>
Explanation: Heat influx is always equal to heat efflux. It is a function of space coordinates only.
3 - Question
Which of the following is an example of steady state heat transfer?
a) Boilers and turbines<br/>
b) Cooling of I.C engine<br/>
c) Chilling effect of cold wind on a warm body<br/>
d) Electric bulb cools down by the surrounding atmosphere
View Answer
Answer: d<br/>
Explanation: System is a perfect black body.
4 - Question
Heat transfer in a long, hollow cylinder which is maintained at uniform but different temperatures on its inner and outer surfaces may be assumed to be taking place in which direction?
a) Axial only<br/>
b) Unpredictable<br/>
c) Radial only<br/>
d) No heat transfer takes place
View Answer
Answer: c<br/>
Explanation: Ambient temperature is uniform on the periphery of cylinder and temperature is uniform. So it takes place in the radial direction only.
5 - Question
Heat transfer takes place according to which law?
a) Newton’s law of cooling<br/>
b) Second law of thermodynamics<br/>
c) Newton’s second law of motion<br/>
d) First law of thermodynamics
View Answer
Answer: b<br/>
Explanation: Second law states about heat transfer between source and sink.
6 - Question
Heat transfer takes place in liquids and gases is essentially due to
a) Radiation
b) Conduction
c) Convection
d) Conduction as well as convection
View Answer
Answer: c<br/>
Explanation: Convection is a process by which thermal energy is transferred between solid and fluid flowing through it.
7 - Question
The appropriate rate equation for convective heat transfer between a surface and adjacent fluid is prescribed by
a) Newton’s first law<br/>
b) Wein’s displacement law<br/>
c) Kirchhoff’s law<br/>
d) Newton’s law of cooling
View Answer
Answer: d<br/>
Explanation: The rate equation used to describe the mechanism of convection is called Newton’s law of cooling when the solid surface is cooled by the fluid.
8 - Question
Identify the wrong statement
a) The process of heat transfer is an irreversible process<br/>
b) For heat exchange, a temperature gradient must exist<br/>
c) A material medium is not necessary for heat transmission<br/>
d) Heat flow doesn’t depend on temperature
View Answer
Answer: d<br/>
Explanation: Heat flows from higher to lower temperature.
9 - Question
During a cold winter season, a person prefers to sit near a fire. Which of the following modes of heat transfer provides him the maximum heat?
a) Conduction from the fire<br/>
b) If it is near the fire, convection sounds good<br/>
c) Convection and radiation together<br/>
d) Radiation will provide quick warmth
View Answer
Answer: d
Explanation: Heat transfer by radiation can occur between two bodies even when they are separated by a medium colder than both of them.
10 - Question
Most unsteady heat flow occurs
a) Through the walls of the refrigerator<br/>
b) During annealing of castings<br/>
c) Through the walls of the furnace<br/>
d) Through lagged pipe carrying steam
View Answer
Answer: b<br/>
Explanation: Under steady state condition, with time there is a change in temperature i.e. temperature field is a function of space and time.