CONVECTION MULTIPLE CHOICE QUESTIONS (MCQ) WITH ANSWERS
CONVECTION MULTIPLE
CHOICE QUESTIONS
(MCQ) WITH ANSWERS
MCQ increase understanding of basic
concepts. It increases the clarity. Then it
becomes easy to apply the fundamentals
in real life.

Free convection is due to
(a) Inertia force
(b) Viscous force
(c) Buoyancy force
(d) None
ANS: (c)
2. Free convection is
(a) visible
(b) Invisible
(c) Neither visible nor invisible
(d) None
ANS: (a)
3. Convective heat transfer coefficient in forced convection depends upon
(a) Grashoff’s and Reynolds numbers
(b) Grashoff’s and Prandtl numbers
(c) Prandtl and Reynolds numbers
(d) None
4. Free convection deals with

(a) Re and Pr

(b) Gr and Re

(c) Nu and Re

(d) None

ANS: (d)
5. Convection is most prominent in

(a) Fluids

(b) Solids

(c) Gases

(d) None

(Ans: a)

Thermal boundary layer is bigger than the hydrodynamic boundary layer when

(a) Pr >>1

(b) Pr=1

(c) Pr <<1

(d) None

ANS: (c)

Free Convective heat transfer coefficient is

(a) Greater than h for forced convection

(b) Equal to h for forced convection

(c) Less than h for forced convection

(d) None

ANS: (c)

Reynolds number = 5 x 10^{5}

(a) Where laminar flow starts

(b) Where laminar flow ends

(c) Where turbulent flow starts

(d) None

ANS: (b)
9. Real example of the forced convection is

(a) Water moving in a container being heated

(b) Flow of blood in the human body

(c) Flow of water in a river

(d) None

ANS: (b)
10. Reynolds number is the ratio of

(a) Inertia force/gravitational force

(b) Viscous force/inertia force

(c) Buoyancy force/viscous force

(d) None

ANS: (d)
11.Product of Grashoff’s and Prandtl number is used in

(a) Forced convection

(b) Free convection

(c) Free as well as in forced convection

(d) None

ANS: (b)
12. During free convection , motion is caused by

(a) Pump in case of a liquid

(b) A blower in case of a gas

(c) Buoyancy force

(d) None

ANS: (c)
13.Practical example of free convective heat transfer is

(a) Flow of heat in the evaporator of an air conditioner

(b) Flow of heat in the boiler for making steam

(c) Flow of heat from the car radiator

(d) None

ANS: (a)

Forced convection is governed by
(a) Grashoff’s Number
(b) Reynolds Number
(c) Reynolds and Prandtl Number
(d) None
ANS: (b)

Prandtl number will be least for
(a) Water
(b) Air
(c) Liquid metal
(d) None
ANS: (c )

Critical Reynolds number in pipe flow is
(a) 1900
(b) 5 lac
(c) 4000
(d) None
ANS: (d)

Free convection Vs forced convection deals with
(a) (Nu x Pr) Vs (Re x Pr)
(b) (Gr x Pr) Vs (Re x Nu)
(c) (Gr x Pr) Vs (Re x Pr)
(d) None
ANS: (c )

The relation for Prandtl number is
(a) μ k/c_{p}
(b) μ ρ/k
(c) μ C_{p}/k
(d) None
ANS: (c )

Grashoff’s Number is
(a)Inertia force)/Viscous force
(b) (Inertia force x Buoyancy force)^{2}/(Viscous force)^{2}
(c) (Inertia force)^{2} /( Buoyancy force x Viscous force)
(d) None

ANS: (b)
20. Reynolds number is given by

(a) (Inertia force x Buoyancy force)/(Viscous force)^{2}

(b) Viscous force/inertia force

(c) Inertia force/viscous force

(d) None

ANS: (c )
21. Definition of Prandtl number is the ratio of

(a) Thermal conductivity/Thermal diffusivity

(b) Thermal diffusivity/Thermal conductivity,
© Thermal diffusivity/Momentum diffusivity
(d) None
ANS: (c )
https://www.mesubjects.net/wpadmin/post.php?post=2742&action=edit Q. ANS. CONVECTION
https://www.mesubjects.net/wpadmin/post.php?post=630&action=edit CONVECTION HEAT TRANSFER