MCQ: HEAT TRANSFER

 

https://www.mesubjects.net/wp-admin/post.php?post=7462&action=edit    Dimensionless num HT

https://www.mesubjects.net/wp-admin/post.php?post=7420&action=edit        HT Symbols-2

https://www.mesubjects.net/wp-admin/post.php?post=7414&action=edit         HT Symbols-1

https://www.mesubjects.net/wp-admin/post.php?post=6732&action=edit        PTU HT Paper Sol B

https://www.mesubjects.net/wp-admin/post.php?post=6434&action=edit       PTU HT Paper Sol A

https://www.mesubjects.net/wp-admin/post.php?post=6261&action=edit            Fin HT

 

MCQ: HEAT TRANSFER-2

MCQ on heat transfer helps in clear and deep understanding. Thus more MCQ should be learnt to further increase of knowledge of heat transfer.

 

  1. Law for the monochromatic radiation emissive power is

(a) Stephen’s Boltzmann Law

(b) Planck’s Law

(c) Wien’s displacement Law

(d)None

ANS: (b)

  1. Radiosity is defined as

  • (a) Total reflected radiations

  • (b) Total emitted radiations

  • (c) Difference of emitted and reflected radiations

  • (d) None

  • ANS: (b)

  1. Absorptivity is zero for an opaque

  • (a) Black body

  • (b) White Body

  • (c) Grey body

  • (d) None

  • ANS: (b)

  1. As per Kirchhoff’s law

  • (a) Radiosity = absorptivity

  • (b) Reflectivity = absorptivity

  • (c) Emissivity= absorptivity

  • (d) None

  • ANS: (c)

  1. Free convection deals with

  • (a) Re and Pr

  • (b) Gr and Re

  • (c) Nu and Re

  • (d) None

  • ANS: (d)

  1. Thermal boundary layer is bigger than the hydrodynamic boundary layer when

  • (a) Pr >>1

  • (b) Pr=1

  • (c) Pr <<1

  • (d) None

  • ANS: (c)

  1. 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)

  1. Reynolds number = 5 x 105

  • (a) Where laminar flow starts

  • (b) Where laminar flow ends

  • (c) Where turbulent flow starts

  • (d) None

  • ANS: (b)

  1. Rate of heat transfer is

  • (a) More in drop-wise than  film-wise condensation

  • (b) Equal in drop-wise and film-wise condensation

  • (c) Less in drop-wise than film-wise condensation

  • (d) None

  • ANS: (a)

  1. Critical heat flux in pool boiling lies in

  • (a) First regime

  • (b) Second regime

  • (c) Third regime

  • (d) None

  • ANS: (c)

  1. Rate of heat transfer will be

  • (a) More in pool boiling than in flow boiling

  • (b) More in flow boiling than in Pool boiling

  • (c) Equal in pool and flow boiling

  • (d) None

  • ANS: (b)

  1. Boiling and condensation temperatures for water are

  • (a) Equal

  • (b) Greater in boiling

  • (c) Less in boiling

  • (d) None

  • ANS: (a)

  1. The units of overall heat transfer coefficient are

  • (a) W/m0C

  • (b) W/m2 0C

  • (c) W/s m 0C

  • (d) None

  • ANS:(b)

  1. Overall heat transfer coefficient accounts for

  • (a) Only conduction and convection

  • (b) Radiation and conduction

  • (c) Radiation and convection

  • (d) None

  • ANS: (d)

  1. 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)

  1. 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)

  1. Critical radius of insulation for a wire will be

  • (a) 2k/h0

  • (b) 3k/ h0

  • (c) k/ h0

  • (d) None

  • ANS:(c)

  1. Thermal conductivity is rate of heat transfer

  • (a) Per unit area/per unit temperature/per unit wall thickness

  • (b) Per unit area /per unit wall thickness

  • (c) Per unit area/per unit temperature difference/per unit wall thickness

  • (d) None

  • ANS:(c)

  1. Thermal diffusivity is the ratio of

  • (a) Thermal conductivity and kinematic viscosity

  • (b) Thermal conductivity and Biot number

  • (c) Thermal conductivity and temperature gradient

  • (d) None

  • ANS:(d)

  1. 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)

 

21. Which Law gives the monochromatic emissive power?

(a) Stefan’s Boltzmann Law

(b) Kirchhoff’s Law

(c) Wien’s Displacement Law

(d) None

ANS: (d)

 

22. All types of radiations are emitted from a body at

(a) Room temperature

(b) Boiling temperature of water

(c) Melting temperature of steel

(d) None

ANS: (d)

  1. Radiations are more harmful with

(a) Large wavelengths

(b) Short wavelengths

(c) Large as well as short wavelengths

(d) None

ANS: (b)

  1. The shape factor F12 in radiation is the ratio of

(a) Radiations falling on body 1 from body 2 to the radiations emitted from body 1

(b) Radiations falling on body 1 from body 1 to radiations emitted from body 2

(c) Radiations falling on body 2 from body 1 to radiations emitted from body 1

(d) None

ANS: (c)

  1. Shape factor is zero for a

(a) Concave body

(b) Convex body

(c) Concave as well as convex body

(d) None

  1. Shape factor depends on the

(a) Shape only

(b) Shape and size of the bodies

(c) Shape, size and orientation of the bodies

(d) None

ANS:(c)

  1. Radiation exchange between two grey bodies is given by

(a) (Eg1 – Eg2)/[(1-ϵ1)/ϵ1 A1) + 1/A1 F12 + (1-ϵ2)/ϵ2 A2)]

(b) (Eb1 – Eb2)/[(1-ϵ1)/ϵ1 A1) + 1/A1 F12 + (1-ϵ2)/ϵ2 A2)]

(c) (Eg1 – Eg2)/[(1/ϵ1 + + 1/ϵ2 –1]

(d) None

ANS: (b)

  1. Critical Reynolds number for forced convection over a flat plate is equal to

(a) 1 lac

(b) 3 lacs

(c) 5 Lacs

(d)None

ANS: (c)

  1. Flow is laminar in free convection if the product of Gr.Pr is

(a) ≥109

(b) ≥108

(c) ≤108

(d) None

ANS: (c)

  1. Value of Reynolds number for a turbulent flow in a pipe is

(a) 2100

(b) 10000

(c) 5 Lacs

(d) None

ANS: (d)

  1. Reynolds number is the ratio of the

(a) Viscous force/ Inertia force

(b)Viscous force/Gravitational force

(c) Inertia force/ viscous force

(d) None

ANS:(c)

  1. Prandtl Number is given by the relation

(a) ρ Cp

(b) μ/ρ Cp

(c) k/ρ Cp

(d) None

ANS: (d)

  1. Critical heat flux is there when excess temperature is

(a) 50C

(b) 100C

(c) 300C

(d) None

ANS: (c)

  1. Boiling is a process of converting liquid into vapor

(a) On cooling alone

(b) On heating alone

(c) On heating as well as on cooling

(d) None

ANS: (b)

  1. Free convection is due to

(a) Inertia force

(b) Viscous force

(c) Buoyancy force

(d) None

ANS: (c)

  1. Free convection is

(a) visible

(b) Invisible

(c) Neither visible nor invisible

(d) None

ANS: (a)

  1. Surface resistance for a black body is

(a) Twice of a same size grey body

(b) Same as for a same size grey body

(c) Zero

(d) None

  1. Space resistance depends on

(a) Distance between the two bodies

(b) Orientation of the two bodies with respect to each other

(c) On the shape factor

(d) None

  1. The wavelength at the peak value of monochromatic emissive power

(a) Increases with the increase of temperature

(b) Decreases with the decrease of temperature

(c) Increases with the decrease of temperature

(d) None

ANS: (c)

  1. 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