Heat Transfer QUESTIONS AND ANSWERS

Mechanical Engineering : Heat Transfer QUESTIONS AND ANSWERS :: part2 : 16 to 20

Following Mechanical Engineering Multiple choice objective type questions and answers will help you in BSNL JTO, GATE 2024 and IES 2024 examinations :

16.The ratio of heat flow Q1/Q2 from two walls of same thickness having their thermal conductivities as ATj - 2K2 will be

0.5

0.25

4.0

17.Thermal conductivity of a material may be defined as the

quantity of heat flowing in one second through one cm cube of material when opposite faces ^re maintained at a temperature difference of 1�C

quantity of heat flowing in one second through a slab of the material of area one cm square, thickness 1 cm when its faces differ in temperature by 1�C

heat conducted in unit time across unit area through unit thickness when a temperature difference of unity is maintained between opposite faces

all of the above

none of the above.

18.In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by

convection

radiation

conduction

both convection and conduction

none of the above.

19.Two balls of same material and finish have their diameters in the ratio of 2 : 1 and both are heated to same temperature and allowed to cool by radiation. Rate of cooling by big ball as compared to smaller one will be in the ratio of

1 :1

2: 1

1 : 2

4 : 1

1 : 4.

20.Heat transfer by radiation mainly depends upon

its temperature

nature of the body

kind and extent of its surface

all of the above

none of the above.

More Heat Transfer QUESTIONS AND ANSWERS available in next pages