STEADY STATE HEAT CONDUCTION MULTIPLE CHOICE QUESTIONS (MCQ) WITH ANSWERS
STEADY STATE HEAT CONDUCTION
MULTIPLE CHOICE QUESTIONS
(MCQ) WITH ANSWERS
MCQ on steady state heat conduction
help to understand concepts in a better
manner. Steady state heat Conduction
takes place in solids by physical contact.
Conduction is invisible mode of heat
transfer. It depends on temperature
difference. Larger is the temperature
difference, greater is the rate of heat
transfer.
Fig. Conduction through a single Plain Wall (linear Temperature Variation)
Fig. Conduction through a composite wall (Linear Temperature Variation)
Fig. Conduction through a Cylinder (Logarithmic Temperature Variation)
_{}
_{Fig. Conduction through a Sphere (}Hyperbolic Temperature Variation)
Fig. Critical Radius of insulation, For a cylinder r_{c} = k/h_{o} and for a sphere, r_{c}=2k/h_{0}

During steady state heat conduction, there is a physical motion of the
(a) Crystal lattice
(b) Main body
(c) Crystal lattice as well as main body
(d) None
ANS: (a)
2. Steady state heat conduction takes place in
(a) Solids only
(b) Liquids only
(c) Gases only
(d) None
ANS: (a)
3. Critical thickness insulation stands for
(a) Minimum rate of heat transfer
(b) Maximum rate of heat transfer
(c) Minimum as well as maximum rate of heat transfer
(d) None
ANS: (b)
4. Biot number is the ratio of
(a) External thermal resistance to internal thermal resistance
( b) Internal thermal resistance to external thermal resistance
(c) Rate of conductive HT/Rate of Convective HT
(d) None
ANS: (b)
5. In steady state conduction heat transfer, there is constant
(a) Rate of heat transfer with respect to time
(b) Temperature with respect to time
(c) Rate of heat transfer and constant temperature w r t time
( d) None
ANS: (c)
6. Thermal conductivity is the rate of heat transfer
(a) Per unit area per unit thickness
(b) Per unit area per unit temperature difference
(c) Per unit area per unit temperature difference and per unit wall thickness
( d), None
ANS: (c )
7. Pure metals thermal conductivity increases
(a)With the increase of temperature
(b) With the increase of pressure
(c) With the increase of both temperature and pressure
(d) None
ANS: ©
8. Heat transfer in a car radiator consists of
(a)(Conduction + convection)
(b) (Convection+ Conduction + convection)
(c) Radiation
(d) None
ANS: (c )
9. Internal heat generation is found in
(a) In a car radiator
(b) In an evaporator of a refrigerator
(c) In the condenser of an air conditioner
(d) None
ANS: (d)
10. Example of steady state conduction is in
(a) Atmosphere
(b) Hot car engine
(c) Hot cup of coffee
(d) None
ANS: (d)
11. Variation of temperature in steady state heat conduction through a wall is
(a) Non linear
(b) Linear
(c) Parabolic
(d) None
ANS: (b)

Temperature variation in Newtonian heating of a solid is
(a) Exponential
(b), Linear
(c) Parabolic
(d) None
ANS: (a)
13. Unit of temperature used in steady state heat conduction and convection is
(a) Degree centigrade
(b) Kelvin
(c) Both degree centigrade and Kelvin
(d) None
ANS: (a)
14. Range of thermal conductivity of pure metals is

Firstly 10 to 200

Secondly 10 to 300

Thirdly 10 to 400

None
ANS: (c )
15. Range of thermal conductivity for insulating & building material is

Firstly 023 to 5.9

Secondly 023 to 3.9

Thirdly 023 to 2.9

None
ANS: (c )
16. Range of thermal conductivities for liquids is

1 to 1.0

2 to 0.6

6 to 1.6

None
ANS: (b)
17. Range of thermal conductivities for gases and vapors

Firstly 006 to 0.1

Secondly 006 to 0.01

Thirdly 006 to 0.023

None
ANS: (c )
18. Thermal conductivity ‘k’, electrical conductivity ‘σ’ & absolute temperature ‘T’, the ratio k/σ T is

Firstly 45 x 10^{+8}

Secondly 45 x 10 ^{8}

Thirdly 45 x 10^{8 to +8}

None
ANS: (b)
19. The ratio of thermal conductivities of good conductors and good insulators is

Firstly 10^{2}

Secondly 10^{3}

Thirdly 10^{4}

None
ANS: (c )
20. The ratio of electrical conductivity of good conductors and good insulators is

Firstly 10^{4}

Secondly 10^{14}

Thirdly 10^{24}

None
ANS: (c )
24. Unit of thermal resistance is

(a)W/m ^{o }C

(b) W/m^{2 o }C

(c) W/K

(d) None

ANS: (a)
Q.25 Critical radius of insulation refers to
(a) Minimum rate of heat transfer
(b) Maximum rate of heat transfer
(c) Constant rate of heat transfer
(d) None
(Ans: b)
26. Critical radius of insulation for a cylinder is equal to
(a) 3k/h_{o}
(b) 2k/h_{o}
(c) 1k/h_{o}
(d) None
(Ans: c)
27. Critical radius of insulation for a sphere is equal to
(a) 3k/h
(b) 2k/ho
(c) 1k/ho
(d) None
(Ans: b)
28. Critical radius of insulation for a plane wall is equal to
(a) 3k/h
(b) 2k/ho
(c) 1k/ho
(d) None
(Ans: d)
29. Thermal conductive resistance of a plane wall in steady state heat conduction is
(a) x/kA
(b) xL/kA
(c) h L/k
(d) None
(Ans: a)
30. Thermal convective resistance is
(a) x/kA
(b) 1/hA
(c) hL/k
(d) None
(Ans:b)
31. Thermal resistance of combined conduction and convection is
(a) U/kA
(b) L/UA
(c) 1/UA
(d) None
(Ans: c)
32. Increase in thermal diffusivity stands for
(a) Faster heat diffusion
(b) Slower heat diffusion
(c) Constant heat diffusion
(d) None
(ANS: a)
33. Biot number deals with
(a) Steady state heat conduction
(b) Unsteady state heat conduction
(c) constant rate of heat conduction
(d) None
(Ans: b)
34. Biot number
(a) Varies with time
(b) Varies directly with k
(c) Varies inversely with k
(d) None
(Ans: c)
35. Conductive resistance in a pipe of single wall is
(a) ln(r_{o}/r_{i} )/2π kL
(b) ln(r_{o}/r_{i} )/π kL
(c) ln(r_{o}/r_{i} )/2πr kL
(d) None
(Ans: a )
35. Thermal resistance for a single wall hollow sphere will be
(a) (r_{o} –r_{i})/4πk r_{i}r_{o}
(b) (r_{o} –r_{i})/2πk r_{i}r_{o}
(c) (r_{o} –r_{i})/6πk r_{i}r_{o}
(d) None
(Ans: a)
36. Variation of thermal conductivity of a non conductor with temperature is
(a) k_{o}(1 + β t)
(b) k_{o}(1 — βt)
(c) k_{o}(1 ± βt)
(d) None
(Ans: a)
Q37. Poisson’ equation in steady state heat conduction deals with
(a) Steady state heat conduction
(b) Unsteady state heat conduction
(c) Steady as well as unsteady states of conduction
(d) None
(Ans: a)
38.Laplace equation in heat transfer deals with
(a) Steady state conduction heat transfer
(b) Unsteady state conduction heat transfer
(c) Steady as well as unsteady states conduction heat transfer
(d) None
(Ans: a)
39. Poisson’ equation in heat transfer deals with
(a) Internal heat generation
(b) External heat generation
(c) Internal as well as external heat generation
(d) None
(Ans: a)
40. Laplace equation in heat transfer deals with
(a) Internal heat generation
(b) External heat generation
(c) Internal as well as external heat generation
(d) None
(Ans: d)
41. Rectangular coordinates used in heat transfer are
(a) r, θ, φ
(b) r, θ, z
(c) x, y, z
(d) None
(Ans:c)
42. Cylindrical coordinates used in heat transfer are
(a) r, θ, φ
(b) r, θ, z
(c) x, y, z
(d) None
(Ans: b)
43. Spherical coordinates used in heat transfer are
(a) r, θ, φ
(b) r, θ, z
(c) x, y, z
(d) None
(Ans: a)
44. Size of the element in rectangular coordinates in the derivation of 3D conduction equation is
(a) r dθ, dr, dz
(b) dx, dy, dz
(c) r dθ, dr, r sinθ dφ
(d) None
(Ans: b)
45. Size of the element in spherical coordinates in the derivation of 3D steady state heat conduction equation is
(e) r dθ, dr, dz
(f) dx, dy, dz
(g) r dθ, dr, r sinθ dφ
(h) None
(Ans: c)
46. Size of the element in cylindrical coordinates in the derivation of 3D conduction equation is
(i) r dθ, dr, dz
(j) dx, dy, dz
(k) r dθ, dr, r sinθ dφ
(l) None
(Ans: a)
47. Poisson’ equation in conduction heat transfer deals with
(a) Steady state conduction heat transfer
(b) Unsteady state conduction heat transfer
(c) Steady as well as unsteady states conduction heat transfer
(d) None
(Ans: a)
48. Laplace equation in heat transfer deals with
(a) Steady state conduction heat transfer
(b) Unsteady state conduction heat transfer
(c) Steady as well as unsteady states of conduction heat transfer
(d) None
(Ans: a)
49. Poisson’ equation in steady state heat conduction deals with
(a) Internal heat generation
(b) External heat generation
(c) Internal as well as external heat generation
(d) None
(Ans: a)
50. Laplace equation in steady state heat conduction deals with
(a) Internal heat generation
(b) External heat generation
(c) Internal as well as external heat generation
(d) None
(Ans: d)
51. Rectangular coordinates used in steady state heat conduction are
(a) r, θ, φ
(b) r, θ, z
(c) x, y, z
(d) None
(Ans: c)
52. Cylindrical coordinates used in conduction heat transfer are
(a) r, θ, φ
(b) r, θ, z
(c) x, y, z
(d) None
(Ans: b)
53. Spherical coordinates used in conduction heat transfer are
(a) r, θ, φ
(b) r, θ, z
(c) x, y, z
(d) None
(Ans: a)
54. Size of the element in rectangular coordinates in the derivation of 3D conduction equation is
(a) r dθ, dr, dz
(b) dx, dy, dz
(c) r dθ, dr, r sinθ dφ
(d) None
(Ans: b)
55. Size of the element in spherical coordinates in the derivation of 3D conduction equation is
(e) r dθ, dr, dz
(f) dx, dy, dz
(g) r dθ, dr, r sinθ dφ
(h) None
(Ans: c)
56. Size of the element in cylindrical coordinates in the derivation of 3D conduction equation is
(i) r dθ, dr, dz
(j) dx, dy, dz
(k) r dθ, dr, r sinθ dφ
(l) None
(Ans: a)
57. Conduction with internal heat generation is found in a


Pressure cooker

Indane gas cylinder

Geyser

None

ANS: (c )
58. Conduction with internal heat generation is found in a


Washing clothes with hot water

Making rice on gas

Boiling of potatoes

None

ANS: (d)
59. Conduction with internal heat generation is found in a


Physical reaction

Chemical reaction

Physical & chemical reaction

None

ANS: (b)
60. Conduction with internal heat generation is found in a


Nuclear reactor

Radiation shield

Umbrella

None

ANS: (a)
61. The following is the case of internal heat generation


Conversion of pressure energy into kinetic energy

Change of kinetic energy into potential energy

Conversion of electrical energy into thermal energy

None

ANS: (c )
62. The equation for steady state heat conduction with internal heat generation is


when d^{2}t/dx^{2} –q_{g}/k=0

if d^{2}t/dx^{2} + q_{g}/k=0

d^{2}t/dx^{2} q_{g}/k=0

None

ANS: (b)
63. Case of a plane wall with uniform heat generation is


Unsteady state conduction

Steady state conduction

Steady & unsteady state conduction

None

ANS: (b)
64. Case of a plane wall with uniform heat generation is


One dimensional heat conduction

2dimensional heat conduction

3dimensional heat conduction

None

ANS: (a)
65. Temperature variation in a plane wall with uniform heat generation is


Linear

Parabolic

Curvilinear

None

ANS: (b)
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