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St.Peter’s Engineering College ENGINEERING PHYSICS HAND BOOK
SYLLABUS UNIT-I
1. Crystallography: Ionic Bond, Covalent Bond, Metallic Bond, Hydrogen Bond, Vander-Waal’s Bond, Calculation of Cohesive Energy of diatomic molecule- Space Lattice, Unit Cell, Lattice Parameters, Crystal Systems, Brava is Lattices, Atomic Radius, Co-ordination Number and Packing Factor of SC, BCC, FCC, Miller Indices, Crystal Planes and Directions, Inter Planar Spacing of Orthogonal Crystal Systems, Structure of Diamond and NaCl. 2. X-ray Diffraction & Defects in Crystals: Bragg’s Law, X-Ray diffraction methods: Laue Method, Powder Method: Point Defects: Vacancies, Substitution, Interstitial, Frenkel and Schottky Defects, line defects (Qualitative) & Burger’s Vector.
UNIT-II 3. Principles of Quantum Mechanics: Waves and Particles, de Broglie Hypothesis, Matter Waves, Davisson and Germer’s Experiment, Heisenberg’s Uncertainty Principle, Schrödinger’s Time Independent Wave Equation – Physical Significance of the Wave Function – Infinite square well potential extension to three dimensions 4. Elements of Statistical Mechanics& Electron theory of Solids: Phase space, Ensembles, Micro Canonical , Canonical and Grand Canonical Ensembles - Maxwell-Boltzmann, Bose-Einstein and Fermi-Dirac Statistics(Qualitative Treatment), Concept of Electron Gas, , Density of States, Fermi Energy- Electron in a periodic Potential, Bloch Theorem, Kronig-Penny Model (Qualitative Treatment), E-K curve, Origin of Energy Band Formation in Solids, Concept of Effective Mass of an Electron, Classification of Materials into Conductors, Semi Conductors & Insulators.
UNIT-III 5. Dielectric Properties: Electric Dipole, Dipole Moment, Dielectric Constant, Polarizability, Electric Susceptibility, Displacement Vector, Electronic, Ionic and Orientation Polarizations and Calculation of Polarizabilities: Ionic and Electronic - Internal Fields in Solids, Clausius - Mossotti Equation, Piezo -electricity and Ferro- electricity. 6. Magnetic Properties & Superconducting Properties: Permeability, Field Intensity, Magnetic Field Induction, Magnetization, Magnetic Susceptibility, Origin of Magnetic Moment, Bohr Magnet on, Classification of Dia, Para and Ferro Magnetic Materials on the basis of Magnetic Moment, Domain Theory of Ferro Magnetism on the basis of Hysteresis Curve, Soft and Hard Magnetic Materials, Properties of Anti-Ferro and Ferri Magnetic Materials and their Applications, Superconductivity, Meissner Effect, Effect of Magnetic field, Type-I & Type-II Superconductors, Applications of Superconductors
UNIT-IV 7.Optics: Interference-Interference in thin films(Reflected light), Newton rings experiment- Fraunhofer diffraction due to single slit, N-slits, Diffraction grating experiment , Double refraction-construction and working, Nicol’s Prism 8. Lasers & Fiber Optics: Characteristics of Lasers, Spontaneous and Stimulated Emission of Radiation, Einstein’s Coefficients and Relation between them, Population Inversion, Lasing Action, Ruby Laser, Helium-Neon Laser, Semiconductor Diode Laser, Applications of Lasers- Principle of Optical Fiber, Construction of fiber, Acceptance Angle and Acceptance Cone, Numerical Aperture, Types of Optical Fibers: Step Index and Graded Index Fibers, Attenuation in Optical Fibers, Application of Optical Fiber in communication systems.
UNIT-V: 9. Semiconductor Physics: Fermi Level in Intrinsic and Extrinsic Semiconductors, Calculation of carrier concentration in Intrinsic &, Extrinsic Semiconductors, Direct and Indirect Band gap semiconductors, Hall Effect- Formation of PN Junction, Open Circuit PN Junction, Energy Diagram of PN Diode, Diode Equation, I-V Characteristics of PN Junction diode, Solar cell, LED & Photo Diodes. Acoustics of Buildings & Acoustic Quieting:, Reverberation and Time of Reverberation, Sabine’s Formula for Reverberation Time, Measurement of Absorption Coefficient of a Material, Factors Affecting The Architectural Acoustics and their Remedies
10. Nanotechnology: Origin of Nanotechnology, Nano Scale, Surface to Volume Ratio, Quantum Confinement, Bottom-up Fabrication: Sol-gel, Top-down Fabrication: Chemical Vapour Deposition, Characterization by TEM.
LECTURE PLAN
Subject ENGINEERING PHYSICS Faculty
UNIT TOPIC CHAPTERS No. of
Classes Total No
of Classes
Book 1 Book 2 Book 3 Book 4 Book 5
I
Crystallography 8 13
X-ray Diffraction & Defects in Crystals
5
II
Principles of Quantum Mechanics
5 13 Elements of
Statistical Mechanics& Electron theory of Solids
8
III
Dielectric Properties
4
12
Magnetic Properties & Superconducting Properties
8
IV Optics 6
15 Lasers & Fiber Optics
9
V Semiconductor Physics&Acoustics
11 16
Nanotechnology 5 CLASSES REQUIRED FOR COMPLETING SYLLABUS 69
Text Books (According to JNTUH) Book1 Engineering Physics,K. Malik, A. K. Singh, Tata Mc Graw Hill Book Publishers Book2 Engineering Physics, V. Rajendran, Tata Mc Graw Hill Book Publishers
Reference Books (According to JNTUH) Book3 Engineering Physics- P.K.Palanisamy (SciTech Publications (India) Pvt. Ltd., Book4 Applied Physics for Engineers – P. Madhusudana Rao (Academic Publishing company, 2013) Book5 Modern Physics by K. Vijaya Kumar, S. Chandralingam: S. Chand & Co.Ltd Book6 Applied Physics – Mani Naidu Pearson Education
1 Solid State Physics – A.J. Dekker (Macmillan). 2 Applied Physics – S.O. Pillai & Sivakami (New Age International (P) Ltd., 3 Modern Physics – R. Murugeshan & K. Siva Prasath – S. Chand & Co. (for Statistical
Mechanics).
4 A Text Book of Engg Physics – M. N. Avadhanulu & P. G. Khsirsagar– S. Chand & Co. (for acoustics).
5 Introduction to Solid State Physics – C. Kittel (Wiley Eastern).
ASSIGNMENT QUESTIONS IN ENGINEERING PHYSICS
UNIT - I 1 Derive an expression for the cohesive energy of a diatomic molecule Remarks 2 Describe the seven crystal systems with neat diagrams? 3 Show that FCC crystals are closely packed structure compared to sc and BCC structures.
4 What are Miller Indices and Miller planes? 5 Deduce the expression for the interplanar distance in terms of Miller indices for a simple
cubic structure.
6 Derive Bragg’s Law of X-ray diffraction.
7 Describe powder method of X-ray diffraction technique to determine the crystal structure.
8 Explain the Frenkel defect and derive the equation of frenkel defect to create energy vacancy.
9 Describe Laue method of X-ray diffraction technique to determine the crystal structure.
UNIT – II 1 What is de-Broglie hypothesis? Find the wavelength λ associated with an electron of mass
M and kinetic energy E.
2 Give in detail the experiment of Davison and Germer in support of the hypothesis.
3 Derive Schrodinger’s time independent wave equation. What is the significance of the wave function ψ.
4 Derive an expression for the particle in a one dimensional potential box 5 Comparison between Maxwell- Boltzmann, Bose -Einstein, Fermi -Dirac statistics.
6 What is black body? Derive the expression for Planck’s law of black body radiation. .
7 Derive the equation for density of states.
8 State Bloch theorem. Describe the kronig-Penney model and find the solution of the wave equation for an electron in crystal lattice.
9 Derive an expression for the effective mass of an electron &hole UNIT – III
1 Define the term electric dipole b) dielectric constant c) dielectric polarization d) dielectric strength e) dielectric breakdown f) loss angle in dielectric
2 What is local field? Derive the necessary expression and extend it to Classius Mosotti equation.
3 Obtain the expression for electronic & ionic polarization? 4 Distinguish between dia, para, ferro, magnetic materials.
5 Explain domain theory of Ferro Magnetism on the basis of hysteresis Curve 6 What is Magnetic Levitation? 7 Explain about Perfect diamagnetism.(Meissner effect)
8 define the terms a) Permeability b) Field intensity c) Magnetic Field d) Magnetization e) Susceptibility.
UNIT – IV 1 Discuss the theory of Newton’s rings &Derive an expression for the diameter of dark
&bright fringes.
2 What is Fraunhofer Diffraction &explain the method of determination of wavelength of spectral lines of given source using plane grating
3 Derive Einstein’s coefficients and explain the relation between them.
4 With the help of suitable diagrams, explain the principle, construction and working of Ruby Laser.
5 Explain the principle, working and construction of semiconductor laser 6 ) Explain the terms numerical aperture and acceptance angle. Obtain mathematical
expressions for acceptance angle and numerical aperture.
7 Give a brief note about the classification of optical fibres for optical communication 8 Calculate the numerical aperture and acceptance angle for an optical fiber with core and
cladding refractive indices being 1.48 and 1.45 respectively.
9 Distinguish between spontaneous and stimulated emissions process of light.(b) What is meant by population inversion? Explain.
UNIT – V 1 What are intrinsic and extrinsic semiconductors? Obtain the expression for electron
concentration in conduction band of intrinsic semiconductors
2 Derive an expression for the density of holes in the valence band of an intrinsic semiconductor
3 Sketch the energy band diagram of n-type and p- Type semiconductors. Obtain the expressions for hole concentration in V.B of p-type and electron concentration in C.B of n- type semiconductors
4 Write a short notes on Led, solar cell, photodiode
5 What are the factors affecting the architectural acoustics and their remedies.
6 What is reverberation and reverberation time and derive Sabine’s formula 7 Explain the measurement of absorption coefficient of a material. 8 Give the physical and chemical properties of nano materials.
9 What are carbon nano tubes? How are they fabricated? Give their applications
UNIT - I SHORT TYPE QUESTIONS
Remarks
1 What are the different types of bonds in solids? Discuss cohesive energy.
2 Define the terms (a) lattice (b) Unit cell (c) Basis d)lattice parameters
3 Distinguish between simple cubic, FCC and BCC structures and find their packing fractions.
4 What are the different crystal systems
5 Derive Bragg’s Law of X-ray diffraction. 6 Explain the significance of burger’s vector. 7 What are the applications of X-ray diffraction 8 What are point defects?
ESSAY TYPE QUESTIONS
1 Derive an expression for the cohesive energy of a diatomic molecule 2 Deduce the expression for the interplanar distance in terms of Miller indices for a simple
cubic structure.
3 Describe the structure of diamond and deduce the packing density for Diamond structure. 4 Describe the seven crystal systems with neat diagrams? 5 Show that FCC crystals are closely packed structure compared to sc and BCC structures.
6 Describe powder method of X-ray diffraction technique to determine the crystal structure.
7 Explain the Frenkel defect and derive the equation of frenkel defect to create energy vacancy.
8 Describe Laue method of X-ray diffraction technique to determine the crystal structure.
9 Discuss the schottky defect in the case of ionic crystals.
UNIT – II SHORT TYPE QUESTIONS
1 Dual nature de Broglie’s matter waves. Describe their properties 2 Explain Physical significance of ψ. 3 Explain Heisenberg uncertainty of Principle. 4 Compare waves & particles.
5 Explain about Fermi energy.
6 Define electron gas& photon gas
7 Explain canonicalµcanonical ensemble
8 State Bloch theorem 8 Discuss the significance of E-K diagram 10 Distinguish between the insulators, semiconductors and conductors based on the band
theory.
ESSAY TYPE QUESTIONS
1 What is de-Broglie hypothesis? Find the wavelength λ associated with an electron of mass M and kinetic energy E.
2 Give in detail the experiment of Davison and Germer in support of the hypothesis. 3 Derive Schrodinger’s time independent wave equation. What is the significance of the
wave function ψ.
4 Derive an expression for the particle in a one dimensional potential box 5 Comparison between Maxwell- Boltzmann, Bose -Einstein, Fermi -Dirac statistics. 6 What is black body?derive the expression for planck’s law of black body radiation. 7 Derive the equation for density of states. 8 Derive an expression for the effective mass of an electron &hole 9 Describe the kronig-Penney model and find the solution of the wave equation for an
electron in crystal lattice.
UNIT-III SHORT TYPE QUESTIONS
1 Define the terms a)electric dipole b) dielectric constant c) dielectric polarization d) dielectric strength e) dielectric breakdown f) loss angle in dielectric
2 Explain the effect of frequency on dielectric material? 3 Derive Classius - Mosotti equation. 4 define the terms a) Permeability b) Field intensity c) Magnetic Field
d) Magnetization e) Susceptibility.
5 Distinguish between Hard and Soft Materials. 6 Write the properties of Anti ferro and ferri magnetic materials
ESSAY TYPE QUESTIONS
1 What is local field? Derive the necessary expression and extend it to Classius Mosotti equation.
2 Obtain the expression for electronic & ionic polarization? 3 Distinguish between dia, para, ferro, magnetic materials. 4 Explain domain theory of Ferro Magnetism on the basis of hysteresis Curve 5 Explain about Perfect diamagnetism.(Meissner effect) 6 Explain about Type1&Type2 superconductors
UNIT-IV SHORT TYPE QUESTIONS
1 Explain the interference phenemenon 2 Explain the characteristics of laser beam 3 Explain the following: a) Life time of an energy level b) Optical pumping process
c) Meta stable states
4 Distinguish between spontaneous and stimulated emissions process of light 5 What is meant by population inversion? Explain 6 Explain the principle behind the propagation of light through the Optical fibres 7 Distinguish between step index and graded index optical fibre. . 8 Write about applications of optical fiber 9 Write a short note on attenuation in fibres
ESSAY TYPE QUESTIONS
1 Discuss the theory of Newton’s rings &Derive an expression for the diameter of dark &bright fringes.
2 What is Fraunhofer Diffraction &explain the method of determination of wavelength of spectral lines of given source using plane grating
3 Derive Einstein’s coefficients and explain the relation between them.
4 With the help of suitable diagrams, explain the principle, construction working of Ruby Laser.
5 Explain the principle, working and construction of semiconductor laser 6 Explain the terms numerical aperture and acceptance angle. Obtain mathematical
expressions for acceptance angle and numerical aperture.
7 Give a brief note about the classification of optical fibres for optical communication 8 Dra Draw the block digram of optical fibre communication system and explain the function of
each block
UNIT-V SHORT TYPE QUESTIONS
1 Explain about intrinsic semiconductor.
2 Ex Explain about extrinsic semiconductor 3 Explain the effect of temperature on resistivity of semi- conductors 4 WW Write the principle of photodiodes 5 What are Nanomaterials? Give the basic principles of Nanoscience and Technology.
6 Discuss about sol-gel technique 7 G Give the physical and chemical propertics of nanomaterials 8 Explain the measurement of absorption coefficient of a material.
9 Give the different application of nanotechnology.
ESSAY TYPE QUESTIONS
1 What are intrinsic and extrinsic semiconductors? Obtain the expression for electron concentration in conduction band of intrinsic semiconductors
2 Derive an expression for the density of holes in the valence band of an intrinsic semiconductor
3 Sketch the energy band diagram of n-type and p- Type semiconductors. Obtain the expressions for hole concentration in V.B of p-type and electron concentration in C.B of n- type semiconductors
4 Write a short notes on Led, solar cell, photodiode
5 Explain the concept of Hall effect 5 What are the factors affecting the architectural acoustics and their remedies.
6 What is reverberation and reverberation time and derive Sabine’s formula 7 Explain the measurement of absorption coefficient of a material. 8 What are carbon nano tubes? How are they fabricated? Give their applications 9 DD Discuss about surface to volume ratio of nanomaterials 10 Explain the fabrication of nanomaterials by PVD & CVD methods
OBJECTIVE TYPE QUESTIONS UNIT-I
1. The nature of binding for crystal with alternate and evenly spaced positive and negative ions is a) ionic b) covalent c) metallic d) dipole 2. Which of the following elements is a covalently bonded crystal ? a) aluminium b) sodium chloride c) germanium d) lead 3. What is the nature of binding in CH4 ? a) covalent b) ionic c) metallic d) dispersion 4. The length of H – H bond is a) 0.074 nm b) 0.01 nm c) 0.037 nm d) 2 nm 5. Which of the following relation gives the potential energy of a diatomic molecule ? a) -a/rm + b/rm b) a/rm – b/rn c) arm + brn d) arm - brn
6. Cohesive energy of solids is
a)
−−n
nm
r
am
0 b)
−−m
mn
r
am
0
c)
−−n
m
r
an
10
d)
−− n
m
r
anm
10
7. Which of the following relation gives the potential energy of a diatomic molecule ? a. arm - brn b. arm + brn
c. nm r
b
r
a − d. mm r
b
r
a +−
8. If r is the radius of the atom in a crystal crystallizing in the simple cubic structure, then the nearest neighbor distance is
a) r/2 b) 4r c) 2r d) none of these 9. The number of lattice points in a primitive cell are a) 1 b) 1/2 c) 2 d) 3/2 10. The nearest neighbour distance in the case of bcc structure is a) (a√3)/2 b) (a√2)/2 c) 2a/√3 d) 2a/√2 11. The co-ordination number in the case of simple cubic crystal structure is a) 12 b) 6 c) 2 d) 1 12. The packing factor of diamond cubic crystal structure is a) 60% b) 56% c) 90% d) none of these 13. The number of molecules present in the unit cell of sodium chloride is a) 5 b) 2 c) 4 d) none of these 14. The packing factor of the fcc structure is a) 52% b) 68% c) 92% d) none of these
15. The bonding energy between two atoms corresponds to a) the maximum of the repulsive energy b) the minimum point in the energy Vs inter atomic distance curve. c) The maximum of the energy Vs inter atomic distance curve. d) The minimum of repulsive force.
16. The bond energy of NaCl molecule is given by the relation E =
a) r
e
0
2
4 ∈−
π b)
00
2
4 r
e
∈−
π c)
00
2
4 r
e
∈π d) 0
204 r∈π
17. A metallic bond differs from a covalent bond in that a) It is not directional b) It is not saturable c) the valence electrons are not attached to any particular atom d) all of the above 18. Which one is the weakest type of bonding in solids ? a) ionic b) covalent c) metallic d) Van der Waals 19. The formation of solid helium is due to the a) Covalent bond b) Dispersion bond c) Hydrogen bond d) Metallic bond 20. When the bond length is decreased, the bond energy a) remains constant b) also decreases c) increases d) none of the above 21. During the formation of a bond a) some energy is lost b) some energy is gained c) energy remains constant d) the total mass decrease 22. Dispersion bonds are formed due to ____________ of positive and negative charges in a molecule.
a) Localised Centers b) Varying centers c) Boath a& b d) None 23. Which bond is available in the three states of matter ? a) Metallic bond b) Covalent bond c) Ionic bond d) Van der Waals bond 24. Give two examples of covalent crystals (a) _________ (b) ___________ 25. Give two examples of ionic crystals (a) ___________ (b) ___________ 26. The distance when energy is minimum is called the ...................... 27. The minimum energy is called ...................... 28. The energy required to remove two atoms into an infinite separation is called 29. In metallic bonds there is attraction between the lattice of ion cores and the ............ 30. Diamond is an example of ...................... bond. 31. Secondary bonds result of ................. Attractions 32. Lithium hydride is an example of __________ Crystal. 33. The number of nearest equidistant neighbours that an atom has in a unit cell is called................... 34. Atomic radius is ................. The distance between the nearest neighbouring atoms in a crystal. 35. Packing factor is the ratio of ................. 36. The unit cell of a simple cube has atoms only at ................. Of the cube. 37. The coordination number of BCC structure is ................. 38. The geometrical features of a crystal, which are represented by lattice points, are called...................... 39. A notation conventionally used to describe lattice points, directions and planes is known as .................. 40. The no. Of families of directions existing in a crystal. (a) 6 (b) 9 (c) 12 (d) 2 41. The formula for angle between two crystal directions [h1 k1 l1] and [h2 k2 l2] of a simple cubic system
...................... 42. Calculate the angle between [111], [011] directions in a cubic system. 43. What are the rules to obtain miller indices of a plane?
44. In a crystal, a plane cuts intercepts at 2a, 3b, and 6c along the three crystallographic axes. Determine the miller indices of the plane.
45. The value of cos2 α + cos2β + cos2 ϒ is (a) 2 (b) -1 (c) 0 (d) 1 46. For a cube, the interatomic spacing d = ...................... 47. What are the interplanar distances for the planes (100), (101) and (111) in a simple cubic lattice? 48. Find the interplanar spacing for the planes (100), (110) and (111) in a BCC. 49. What is the ratio of d100: d110 : d111 in an FCC?
50. Calculate the inter planar spacing for (321) plane in simple cubic lattice with Inter atomic spacing a = 4.12 Å
51. The wave length associated with a moving particle
a) depends upon the charge associated with it. b) Does not depend upon the charge associated with it. c) Depends upon the medium in which the particle travels. d) None of these.
52. A proton and α-particle has the same kinetic energy. If the mass of the α-particle is four times that of a proton, how do their de Broglie wave length compare ?
a) λp = λα/2 b) λp = λα/4 c) λp = 2λα d) λp = 4λα
53. Because of which property of the crystals, x-rays can be diffracted from the crystals. a) random arrangements of atoms b) colour of the crystals c) periodic array of atoms none of these
54. An electron, neutron and proton have the same de Broglie wave lenths; which particle has greater velocity ? a) electron b) proton c) neutron
55. x-rays consist of a) negatively charged particles b) electromagnetic radiation. c) Positively charged particles d) A stream of neutrons
56. x-rays are produced when an element of high atomic weight is bambarded by high energy a) protons b) photons c) neutrons d) electrons
57. If 50 kV is the applied potential in an x-ray tube, then the minimum wavelength of x-rays produced is
a) 0.2 nm b) 2 nm c) 0.2 A& d) 2 A& 58. As the wavelength of x-rays is smaller than that of visible light, the speed of x-rays in vacuum is a) same as that of visible light b) larger than that of visible light c) smaller that that of visible light 59. If the Fermi energy of silver at OK is 5 electron volt, the mean energy of electron in silver at OK is
a) 6 electron volt b) 12 electron volt c) 1.5 electron volt d) 3 electron volt
60. If the Fermi energy of a metal is 1.4 electron volt, the Fermi temperature of the metal is approximately. a) 1.6 × 103K b) 1.6 × 104K c) 1.6 × 105K d) 1.6 × 106K
61. E1 is the lowest energy value of the electron in a one dimensional potential box of side a and E2 is the lowest energy value of the electron in a cubical box of side a/2, then E2/E1 is
a) 12 b) 3 c) 4 d) 2 62. Crystal defects are :
a) point and line defects b) surface defects c) volume defects d) all
63. Point defects are : a) lattice site defects b) compositional defects
c) electronic defects d) all 64. Electrical charge neutrality is maintained in :
a) Schottky defect b) Frenkel defect c) Both a and b d) none 65. Schottky defect may exist in :
a) NaCl crystal b) KCl crystal c) KBr crystal d) all 66. Substitutional defect and interstitial impurity defect belong to :
a) Compositional defect b) Schottky defect c) Frenkel defect d) lattice site defects
67. Non-uniformity of charge or energy distribution in the crystal is referred to as : a) point defect b) electronic defect c) Schottky defect d) Frenkel defect
68. Point defects in crystals are formed by : a) thermal fluctuations b) Large deformation c) bombarding with high energetic particles d) all
69. Edge dislocation and screw dislocation belong to : a) electronic defect b) compositional defects c) line defects d) point defects
70. If the incomplete plane is below the slip plane, then the edge dislocation is : a) Positive b) negative c) both a and b d) none
71. In edge dislocation, the Burger’s vector is _________ to the dislocation line. a) parallel b) at an angle of 450 c) Perpendicular d) at an angle of 600
72. If Ev is the energy required to form a vacancy in the crystal containing ‘N’ atoms at temperature ‘T0, the number of vacancies in the crystal is [KB = Boltzmann constant]
a) N exp
−TK
E
B
V b) N exp
−
V
B
E
TK
c) N exp
TK
E
B
V d) N exp
−TK
E
B
V
2
73. X-ray powder method is usually carried for ________ materials. a) Polycrystalline b) Powder c) single crystal d) amorphous
74. Using powder diffraction ___________ of a crystal can be determined. a) the interatomic spacing b) the interplanar spacing c) both a and b d) none
75. In powder method, _______chromatic X-rays are used. a) mono b) Poly c) both a and b d) none
76. In Laue method, __________X-rays are used. a) monochromatic b) white c) both a and b d) none
OBJECTIVE TYPE QUESTIONS UNIT-II
01. The de Broglie wave length associated with an electron of mass m and accelerated by a potential V is
a)mVe
h
2 b)
h
mve2 c)
Vem
v d)
Vem
h
2
02. The wave length associated with a moving particle e) depends upon the charge associated with it. f) Does not depend upon the charge associated with it. g) Depends upon the medium in which the particle travels.
h) None of these. 03. A proton and α-particle has the same kinetic energy. If the mass of the α-particle is four times that of a proton,
how do their de Broglie wave length compare ? a) λp = λα/2 b) λp = λα/4 c) λp = 2λα d) λp = 4λα
04. Davisson and Germer were the first to demonstrate a) the straight line propagation of light b) the diffraction of photons c) the effective mass of electrons d) none of these
05. Because of which property of the crystals, x-rays can be diffracted from the crystals. a) random arrangements of atoms b) colour of the crystals c) periodic array of atoms d) none of these
6. An electron, neutron and proton have the same de Broglie wave lengths; which particle has greater velocity ? a) electron b) proton c) neutron
7. In the Davission-Germer experiment the hump is most prominent when the electron is accelerated by a) 34 volt b) 54 volt c) 60 volt d) none of these
8. x-rays consist of a) negatively charged particles b) electromagnetic radiation. c) Positively charged particles d) A stream of neutrons
9. x-rays are produced when an element of high atomic weight is bambarded by high energy a) protons b) photons c) neutrons d) electrons
11. If 50 kV is the applied potential in an x-ray tube, then the minimum wavelength of x-rays produced is
a) 0.2 nm b) 2 nm c) 0.2 A& d) 2 A& 12. As the wavelength of x-rays is smaller than that of visible light, the speed of x-rays in vacuum is
a) same as that of visible light b) larger than that of visible light c) smaller that that of visible light
13. If E1 is the energy of the lowest state of a one dimensional potential box of length a and E2 is the energy of the lowest state when the length of the box is halved, then
a) E2 = E1 b) E2 = 2E1 c) E2 = 3E1 d) E2 = 4 E1
14. If the Fermi energy of silver at OK is 5 electron volt, the mean energy of electron in silver at OK is a) 6 electron volt b) 12 electron volt c) 1.5 electron volt d) 3 electron volt
15. If the Fermi energy of a metal is 1.4 electron volt, the Fermi temperature of the metal is approximately. a) 1.6 × 103K b) 1.6 × 104K c) 1.6 × 105K d) 1.6 × 106K
16. E1 is the lowest energy value of the electron in a one dimensional potential box of side a and E2 is the lowest energy value of the electron in a cubical box of side a/2, then E2/E1 is a) 12 b) 3 c) 4 d) 2
17. The eigen value of the energy of a particle in a cubical box is 11 ( h2/8ma2). The quantum numbers of the state are a) (3 1 1) b) (3 0 1) c) (2 2 2) d) (1 1 1)
18. If E is the kinetic energy of the material particle of mass m, then de Broglie wavelength is given by [ ]
a) hmE /2 b) mEh 2/ c) mEh 2 d) None of the above
19. The energy between the nth energy level and the next higher level increases as. [ ] a) 2n En b) n En c) (2n +1) En d) None of the above 20. The normalized wave functionnψ is [ ]
a) a
xn
a
∏sin
2 b)
a
xn
a
∏sin
2 c)
a
xn
a
∏sin
2 d) None
21. Phase space is a _______ dimensional space. a) 3 b) 4 c) 5 d) 6 22. Maxwell-Boltzmann statistics is applicable to a) identical distinguishable particles b) identical indistinguishable particles c) femions d) bosons 23. A point in phase space or µ-space can be represented with a) Six position coordinates b) Six momentum coordinates c) Three position and three momentum coordinates d) Six position and six momentum coordinates 24. A temperature TK, if a particle possess energy Ei then the Maxwell-Boltzmann distribution for it can be
represented as [ α=constant, KB = Boltzman constant ]
a) KBT
Ei
eeα
1 b)
KBT
Ei
ee−
α
1 c)
KBT
Ei
ee α−
1 d)
KBT
Ei
ee−
−α
1
25. Fermi-Dinac distribution is applicable to a) distinguishable particles b) indistinguishable particles c) Both a and b d) None of the above 26. The Fermions possess a spin of
a) integral multiples of h b) half-integral multiples of h
c) They possess any spin d) None of the above
27. The Fermi-dirac distribution function of a particle possessing energy E at temperature TK is
a)
−
− KBT
EE f
e1
1 b)
−
+ KBT
EE f
e1
1 c)
1
1
−
−KBT
EE f
e
d)
−
+ KBT
EE f
e1
1
28. Bose – Einstein statistics is applicable to a) identical distinguishable particles b) identical indistinguishable particles c) Both a and b d) None of the above 29. Bosons possess a spin of
a) integral multiples of h b) half-integral multiples of h
c) They can have any spin d) They will not possess spin
30. The free electron in a metal follow ______ distribution. a) Maxwell-Boltzmann b) Fermi-Dirac c) Bose – Einstein d) None of the above 31. At 0K, the probability of an electron in Fermi energy level is a) 0 b) 0.5 c) 1.0 d) less than 1 32. The probability of an electron in Fermi energy level at non-OK temperature is a) 0 b) 0.5 c) between 0.5 and 1 d) 1.0 33) The average drift velocity vx of electrons in metal is related to the electric field E and collision time, T as
a) m
eEτ
b) τeE
m
c) τeE
m
d) m
eEτ
34) In Kronig – Penney model, the width of allowed bands ___ and the width of forbidden bands ______ with increase of energy [or α a]
a) increases, decreases b) increases, increases
c) decreases, decreases d) decreases, increases
35) In Kronig – Penney model, as the scattering power of the potential barrier, P then the allowed energy bands a) reduces to single energy levels b) reduces to smaller bands c) increases to bigger bands d) none 36) The discontinuities in the energies of free electrons of a metal occur at the ____ of the Brillouin zones. a) middle b) boundaries c) both a & b d) none 37) The effective mass of a free electron is ______ when it occupies higher energy levels of a allowed band of
energies. a) negative b) positive c) low negative d) none 38) The effective mass of an electron has been experimentally determined from a) electron specific heat b) cyclotron resonance experiments c) both a &b d) none
OBJECTIVE TYPE QUESTIONS UNIT-III
1. Mobility of the electron is a) flow of electrons per unit electric field b) reciprocal of conductivity c) average drift velocity per unit electric field d) none of the above
2. According to the classical model of free electron,
a) An electron can have any wave vector, there is no restriction on the number of electrons with the same vector b) The electrons can have restricted values of wave vector c) Only two electrons can have the same wave vector d) The electrons can have spin and can have only two values of the wave vector
3. If τ x is the relaxation time of an electron of mass ‘m’ moving along x-direction. The mobility of the
electrons ( xµ ) is [e=charge on electron]
a) m
e xτ
b) m
e xτ c)
2x
m
eτ d) x
2
e
m
τ
4. If m, e, τ and n are the mass, charge, relaxation time and number of free electrons per unit volume respectively. Then the electrical conductivity is
a) m
ne2τ b) τm
ne2
c) 2me
nτ d) τ2ne
m
5. The cause of electrical resistance of a metal is a) impurities and crystal defects b) thermal vibrations
c) electron scattering and non-periodicity of lattice potentials d) all
6. Quantum free electron theory of metals successfully explains a) Electrical conductivity b) specific heat and thermionic emission c) para magnetism d) all
7. Quantum free electron theory of metals fails to explains a) The difference between conductors, semiconductors and insulators b) Positive Hall coefficient of metals c) Lower conductivities of divalent metals than monovalent metals d) All
8. If a and b are the widths of potential well and barrier, V0 is the height of barrier. If an electron of mass m is
present in such potentials then 2
0
h
bamV represent
π=
2
hh
a) Scattering power of the potential barrier b) The strength with which electrons in a crystal are attracted to the ions c) a and b d) none
9. The velocity of a free electron in a metal is maximum when a) it is present in the bottom energy levels of a allowed band b) it is present in the top energy levels of a allowed band c) it is present in a energy level correspond to point of inflection in a allowed bank d) none
10. At very low temperatures the receptivity of a metal is proportional to ____ power of absolute temperature. a) first b) Second c) third d) fifth
11. Relaxation time may be defined as the time taken by an electron to reduce its velocity to ___ of its initial value.
a) half b) one-third c) (1/e) d) 1/2e 12. According to quantum theory the electrical conductivity of a metal is due to those free electrons which are
very close to a) Fermi surface only b) acceptor energy level c) valance band d) None
13. The average drift velocity vx of electrons in metal is related to the electric field E and collision time, T as
a) m
eEτ
b) τeE
m
c) τeE
m
d) m
eEτ
14. Mobility of the electron is a) flow of electrons per unit electric field b) reciprocal of conductivity c) average drift velocity per unit electric field d) none of the above
15. According to the classical model of free electron, a) An electron can have any wave vector, there is no restriction on the number of electrons with the same
vector b) The electrons can have restricted values of wave vector c) only two electrons can have the same wave vector d) The electrons can have spin and can have only two values of the wave vector
16. If τ x is the relaxation time of an electron of mass ‘m’ moving along x-direction. The mobility of the
electrons ( xµ ) is [e=charge on electron]
a) m
e xτ
b) m
e xτ c)
2x
m
eτ d) x
2
e
m
τ
17. If m, e, τ and n are the mass, charge, relaxtion time and number of free electrons per unit volume respectively. Then the electrical conductivity is
a) m
ne2τ
b) τm
ne2
c) 2me
nτ d) τ2ne
m
18.The cause of electrical resistance of a metal is a) impurities and crystal defects b) thermal vibrations
c) electron scattering and non-periodicity of lattice potentials d) all 19.Quantum free electron theory of metals successfully explains
a) electrical conductivity b) specific heat and thermionic emission
c) para magnetism d) all 20.Quantum free electron theory of metals fails to explains
a) The difference between conductors, semiconductors and insulators b) Positive Hall coefficient of metals c) Lower conductivities of divalent metals than monovalent metals d)All
21.If a and b are the widths of potential well and barrier, V0 is the height of barrier. If an electron of mass m is
present in such potentials then 2
0
h
bamV represent
π=
2
hh
a) Scattering power of the potential barrier b) The strength with which electrons in a crystal are attracted to the ions c) a and b d) none
22.The velocity of a free electron in a metal is maximum when a) it is present in the bottom energy levels of a allowed band b) it is present in the top energy levels of a allowed band c) it is present in a energy level correspond to point of inflection in a allowed bank d) none
23.At very low temperatures the receptivity of a metal is proportional to ____ power of absolute temperature. a) first b) Second c) third d) fifth
24.Relaxation time may be defined as the time taken by an electron to reduce its velocity to ___ of its initial value.
a) half b) one-third c) (1/e) d) 1/2e 25.According to quantum theory the electrical conductivity of a metal is due to those free electrons which are
very close to a) Fermi surface only b) acceptor energy level c) valance band d) None
26.The drift velocity produced by applying electric field of intensity ‘E’ on an electron of mass ‘m’ having
charge ‘e’ is [ cτ - mean collision time]
a) cm
eE
τ−
b) m
eE cτ− c)
eE
m cτ− d) c
eEm
τ−
27. The ratio of electrical and thermal conductivity of metals is known as a) Loerntz number b) Curie constant c) Curie-Weiss constant d) Maxwell constant
28. Transition temperature Tc and critical field Hc for a superconductor are related as a. Hc = H0 (Tc – 1) b. Hc = H0 (Tc +1) c. Tc = T0 [ 1-(H0/Hc)
2] d. Hc = H0 [1- (T/T0)2]
29. Cooper pairs are formed a. at very low temperatures as the thermal energy is not sufficient to disrupt the binding
b. at high temperatures as the thermal energy is sufficient to form the Cooper pair c. none of these
30. The coherence length of the paired electrons is a. 0.25 nm b. 250 nm c. 0.01 nm d. 0.001 nm
31. The magnetic field applied for the destruction of superconductivity is called the (a) Saturation field (b) Critical field (c) Critical temperature (d) Destruction field
32. Omnes observed that the resistivity of mercury vanishes at (a) 4 K (b) 77k (c) 4.2 k (d)Room temperature.
32. Temperature of a superconductor at a given magnetic field compared with the temperature at optimum critical magnetic field is
(a) Smaller (b) always bigger (c) Smaller or bigger depending on the substance (d) No such relation exists
33. Which of the following statements is not true for a superconductor, above Tc
(a) Specific heat is small (b)thermal conductivity is large (c) Entropy is more (d) none
34. Energy of super conducting electron (a) Is much more greater than the energy gap (b) is less than that of energy gap (c) Is less than or equal to energy gap (d)is greater than or equal to energy gap 35. Superconductors are generally
a. ferromagnetic and antiferro magnetic metals b.monovalent metals c. amorphous thin films of Be and Bi d.thin films of barium titanate
36.Hard superconductors observe a. breakdown of Silsbee’s rule b. Incomplete Meissner effect c. high critical field and transition temperature d. all of these
37.Soft superconductors observe a. Meissner effect b. Silsbee’s rule c. both (a) and (b) d. none of these
38.The temperature at which a conductor becomes a super conductor is called a) superconducting temperature b. Curie temperature c) one’s temperature d. Transition temperature 39. The specific heat of a superconducting material shows an abrupt change at T = Tc jumping to a large
value for a. T<Tc b. T>Tc c. T = Tc
40. In superconducting state a. entropy increase and thermal conductivity decreases b. entropy and thermal conductivity decrease c. entropy and thermal conductivity increase d. entropy decreases and thermal conductivity increases.
41. Super conductivity results due to a. Crystal structure having infinite atomic vibrations at OK b. Crystal structure having no atomic vibrations at OK. c. All electrons interacting in the superconducting state. d. All electrons having Fermi energy at OK.
42. The transition temperature of mercury is a. 1 K b. 1.14 K c. 4.12 K d. 9.22 K
43. A super conducting material when placed in a magnetic field will a. attract the magnetic field toward its centre b. repel all the magnetic lines of forces passing through it. c. Attract the magnetic field but transfer it into a concentrated zone d. Not influence the magnetic field
44. Value of critical current density (jC) in a superconductor depends upon a. temperature b. magnetic field strength c. both a) & b) d. Silsbee effect
45. Transition temperature Tc and critical field Hc for a superconductor are related as
a. Hc = H0 (Tc – 1) b. Hc = H0 (Tc +1) c. Tc = T0 [ 1-(H0/Hc)
2] d. Hc = H0 [1- (T/T0)2]
46. The width of the energy gap of a superconductor is maximum at a. OK b. transition temperature c. room temperature d. none of these 47. The width of the energy gap of a superconductor at OK is about a. 0 Joule b. 3.5 kBTc c. kB Tc d. 300 kBTc
48. As the isotopic mass of mercury decreases a. the critical temperature increases slightly b. the critical temperature decreases slightly c. remains constant
49. Cooper pairs are formed a. at very low temperatures as the thermal energy is not sufficient to disrupt the binding
b. at high temperatures as the thermal energy is sufficient to form the Cooper pair c. none of these
50. The coherence length of the paired electrons is a. 0.25 nm b. 250 nm c. 0.01 nm d. 0.001 nm
51. The London penetration depth is given by a. λ = [ m/ns µ0 e
2]1/2 b. λ = [ ns / mµ0 e2]1/2
c. λ = [ ns m µ0 e2]1/2 d. none of these
52. Superconductors are generally a. ferromagnetic and antiferromagnetic metals b. monovalent metals c. amorphous thin films of Be and Bi d. thin films of barium titanate
53. Hard superconductors observe a. breakdown of Silsbee’s rule b. incomplete Meissner effect c. high critical field and transition temperature d. all of these
54. Soft superconductors observe a. Meissner effect b. Silsbee’s rule
c. both (a) and (b) d. none of these
55. The temperature at which a conductor becomes a super conductor is called a. superconducting temperature b. Curie temperature
c. one’s temperature d. Transition temperature 56. The specific heat of a superconducting material shows an abrupt change at T = Tc jumping to a large
value for a. T<Tc b. T>Tc c. T = Tc
57. Dielectrics are : a) metals b) semiconductors c) insulating materials d) none
58. Local electric field is calculated by using the method suggested by : a) Lorentz b) Weiss c) Curie d) Coulomb
59. dielectric material can be polarized by applying _________ field on it. a) magnetic b) gravitational c) electric d) meson
60. Polarization per unit applied electric field is called : a) electric susceptibility b) magnetic susceptibility c) electric polarization d) dielectric constant
61. Piezoelectric effect in quartz crystal is maximum along : a) X-axis b) Y-axis c) Z-axis d) optic axis
62. The unit of dipole moment/unit volume is a. coulomb/metre b. coulomb/metre2 c. coulomb/metre3 d. coulomb
63. When monoatomic gas atom is placed in a uniform electric field E, the displacement of the nucleus is proportional to a. E2 b. E c. E3 d. Independent
64. The flux density is related to the electric field is a. 4πε0 b. 4πε0R c. 4πε0R
3 d. 4πε0R2
65. When a monoatomic gas atom is placed in a uniform electric field E, the resulting induced dipole moment is proportional to a. E b. E2 c. E3 d. independent of E
66. The electronic polarizability αe of a monoatomic gas atom is a) 4πε0 b. 4πε0R c. πε0R
3 d. πε0R2
67. The dipole moment per unit volume of a solid is the sum of all the individual dipole moments and is called a) Polarization of the solid b) Permittivity of the solid c) Electrostatic moment d) None of these
68. The polariztion p in a solid dielectric is related to the electric field E and the electric flux density D by the relation a). E = ε0D + P b). E = E + ε0P c). D = Eε0 + P d). D = ε0 (E+P)
69. For a given dielectric, the electronic polarizability, αe a. increases with temperature b. decreases with temperature c. is not affected by temperature change d. may increase or decrease with temperature
70. In a dielectric, the polarization is a. linear function of applied field b. square function of applied field c. exponential function of applied field d. logarithmic function of applied field
71. In a ferroelectric mateial, as the applied electric field is gradually reduced to zero, the polarization still left is known as a. transition temperature b. Debye temperature c. Fermi temperature d)Curie temperature
72. The factor responsible for sponataneous polarization is a. free electrons b. atoms c. permanent dipoles d. none of these
73. Piezoelectric effect is the production of electricity by a. chemical effect b. varying field c. temperature d. pressure
74. The magnetic dipolemoment is the product of current in the loop and a) flux enclosed by current loop b) square of area enclosed by current loop c) area enclosed by current loop
d) none of these 75. Relative permeability of a medium is the permeability relative to that of
a) water b) vacuum c) iron d) none of these
76. Magnetic susceptibility χ equals a) dipolement per unit volume b) torque per unit area c) magnetization per unit magnetic field intensity d) none of these
77. Magnetic susceptibility has the dimensions of a) Wb/m2 b) Wb/m c) amp/m d) dimension less
78. Magnetic induction B and the magnetic field intensity H are related by a) B = µ0H
2 b) B = µ20H
c) B = µ0µrH d) B = µ0 + H 79. eB/2m is called the
a) Debye angular frequency b) Bohrmagneton c) Larmor angular frequency d) None of these
80. Magnetic susceptibility χ of a magnetic material is given by a) χ = (µr-1) b. χ = M/H c) χ = (µ-µ0)/ µ0 d. B = µ0 (H-M)
81. In a ferromagnetic material, susceptibility is a) Very small and positive b) Very small and negative c) Very large and positive d) Very large and negative
82. The units of magnetic permeability are a) henry/metre b) henry metre c) weber metre d) henry/sec
83. Which of the following material does not have permanent magnetic dipoles ? a) paramagnetic b) diamagnetic c) ferrimagnetic d) anti-ferromagnetic
84. Diamagnetic materials possess a) permanent magnetic dipoles b) no permanent magnetic dipoles c) induced dipole moment d) none of these
85. Interaction between the neighbouring dipoles is negligible in the case of a a) diamagnetic material b) paramagnetic material c) anti ferromagnetic material d) ferri magnetic material
86. Curie – Weiss law is a) χm = C/T b) χm = (C/θ) c) χm = C/(T-θ) d) χm = (T-θ)/C
87. The ferromagnetic Curie temperature of iron is a) 631 K b) 922 K c) 142.8 K d) 1043 K
88. Which of the following materials is used for making permanent magnet a) platinum cobalt b) Alnico V c) carbon steel d) all the three
89. Below the ferromagnetic Curie temperature, the ferromagnetic material exhibits B-H curve in the form of a) B-H loop b) Straight line c) exponential curve d) none of these
90. At Curie temperature, the spontaneous magnetization for ferromagnetic materials is a) infinity b) 1 c)zero d) none of these
91. The temperature below which certain materials are antiferromagnetic and above which they are paramagnetic is called
a) Curie temperature b) Neel temperature c) transition temperature d) Weiss temperature
92. H2O molecule is a .................... Molecule.
93. When a field is applied, dipoles tend to ............... and ................. With the field. 94. Polarization resulting due to the relative displacements of ions is called ................... 95. Electrons in various shells are displaced relative to the nucleus, producing an electric dipole moment
resulting in .............. Polarization. 96. Total polarization α = .................... + .................... + ....................... 97. Ferroelectric material possess .......................... Polarization. 98. At .............................. φ K, the magnetization has a saturation value i.e. all the spins are rigorously
.............................. 99. The excitation of a single spin propagates like a wave and is called ..............................
OBJECTIVE TYPE QUESTIONS UNIT-IV
1. The London penetration depth is given by a. λ = [ m/ns µ0 e
2]1/2 b. λ = [ ns / mµ0 e2]1/2 c. λ = [ ns m µ0 e
2]1/2 d. none of these 2. Intrinsic concentration of charge carriers in a semiconductor is given by
a) T b) T2 c) T3/2 d) 1/T 3. The dependence of the mobility of charge carriers in a semiconductor is given by
a) µ ∝ 1/T b) µ ∝ 1/T3/2 c) µ ∝ T3/2 d) µ∝T2 4. In a P-type Semiconductor, as the density of acceptor atoms Na is increased, the Fermi level shifts
towards the valence band. a) true b) false
5. Donor type impurity is formed by adding impurity fo valency. The diffusion current is proportional to a. square of the applied electric field b. applied electric field c. concentration gradient of charge carriers
6. The depletion region in an open circuited p-n junction contains. a) electrons b) holes c) uncovered immobile impurity ions d) neutralized impurity atoms
7. The density of carriers in a pure semiconductor is proportional to a) exp (-Eg /KBT) b) exp (-2Eg/KBT) c) exp (-Eg/KBT2) d) exp (-Eg/2KBT)
8. In a n-type semiconductor, as the density of acceptor atoms Nd is increased, the Fermi level shifts towards the conduction band
a) true b) false 9.The electrical conductivity of a semiconductor at absolute zero of temperature is
a) finite b) very large c) zero d) none 10. The carrier concentration in an intrinsic semiconductor _______with increase of temperature.
a) increases b) decreases c) remains the same d) none
11. Electrical current in an intrinsic semiconductor is due to : a) conduction band electrons b) valence band holes c) both a) and b) d) none
12. In n-type material, the majority carriers are : a) valence band electrons b) conduction band electrons c) valence band holes d) electrons and holes
13. If the Hall coefficient is negative, then the semiconductor is : a) n-type b) p-type c) intrinsic d) None
14. The output of LED is
a) visible light b) IR light c) current d) Both a and b 15. The ripple factor in half wave rectifier is __________.
a) 80 b) 100 c) 121 d) 150 16. The ripple factor in full wave rectifier is __________.
a) 25 b) 38 c) 48 d) 28
17.The GaAsP direct band gap photo diode emits _________ colour light. a) blue b) Green c) Yellow d) Red
18.The GaAsP indirect band gap photo diode emits _________ colour light. a) blue b) Green c) Yellow d) Red 19.The GaP photo diode emits _________ colour light. a) blue b) Green c) Yellow d) Red 20. The following diode emits light a) LED b) LCD c) Both a and b d) None of the above 21. Liquid crystals are sensitive to a) temperature b) electric field c) mechanical stress d) All the above 22. The reverse current that exists when no light is incident at the junction of a photo diode is known as a) dead current b) dark current c) break down current d) none of the above 23. The current gain in avalanche photo diode after avalanche break down is a) 10 b) 100 c) 1000 d) 50 24.Photo diodes are used in a) alaram circuits b) counting of objects in industries c) both a and b d) None of the above 25. LCD’s a) generate light b) do not generate light. c) alter or control the existing light d) Both b and c 26. The phases in liquid crystals are : a) smetic b) nematic c) cholestic d) all the above 27. The SiC and GaN photo diodes emits _________ colour light. a) blue b) Green c) Yellow d) Red
28. Intrisic concentration of charge carriers in a semiconductor is given by a) T b) T2 c) T3/2 d) 1/T
29. The dependence of the mobility of charge carriers in a semiconductor is given by a) µ ∝ 1/T b) µ ∝ 1/T3/2 c) µ ∝ T3/2 d) µ∝T2
30. In a P-type Semiconductor, as the density of acceptor atoms Na is increased, the Fermi level shifts towards the valence band.
a) true b) false 31. Donor type impurity is formed by adding impurity fo valency.
a) 3 b) 4 c) 5 d) 6 32. The diffusion current is proportional to
a. square of the applied electric field b. applied electric field c. concentration gradient of charge carriers
33. The depletion region in an open circuited p-n junction contains. a) electrons b) holes
c) uncovered immobile impurity ions d) neutralized impurity atoms
34. The density of carriers in a pure semiconductor is proportional to a) exp (-Eg /KBT) b) exp (-2Eg/KBT) c) exp (-Eg/KBT2) d) exp (-Eg/2KBT)
35. In a n-type semiconductor, as the density of acceptor atoms Nd is increased, the Fermi level shifts towards the conduction band
a) true b) false
Exp
−1KT
wh is ____________.
a) The ratio of number of spontaneous to stimulated emissions b) Stimulated to spontaneous emission c) Stimulated emission × spontaneous emission d) None
36. If E2 – E1 = 2.36 ev, the wavelength of radiation is ________ nanometer . a) 750 b) 650 c) 550 d) 450
37. The colour of ruby containing 0.5% Cr, it’s colour is a) Black b) Orange c) Pink d) Yellow
38. In He-Ne laser, the radiation that is emitted is from down ward transition of a) He b) Ne c) both He and Ne d) None
39. The coherence of light is known by the i. visibility of the interference fringes it produces ii. size and nature of the source iii. light intensity of the beam iv. flickering of the light beam
40. The light coming from an ordinary source like a filament bulb is a) coherent, non directional, but powerful
b) non monochromatic, non directional, unpolarized and incoherent c) coherent, non monochromatic, non directional but intense d) non coherent, directional, intense and non monochromatic
41. Cutting and Drilling of metals require high energy sources. The Laser that are used are a) He-Ne Laser b) semi conductor laser c) solid state lasers d) CO2 Laser
42. The semiconductor lasers are not used in a) bar – code reading b) optical communication c) cutting and drilling of metals d) compute printer
43. The purpose of the optical resonator in a laser is a) to provide cover to the active medium b) to provide path for stray atoms c) to provide selectivity of photon states d) to send laser radiation in specified direction
44. In He-Ne lasers a) Oxygen is used to burn and emit light b) the transfer of energy of excitation takes place with by collision of excited helium atoms with neon
atoms c) the helium atoms give the metastable level in between neon energy levels d) the neon atoms under low pressure excite helium atoms
45. Check the correctness of the statements (A) The gain of a laser source in the active medium depends on the population difference. (B) The purpose of reflectors in the laser is to deflect the photons from the active medium
a) (A) and (B) are wrong b) (A) is wrong and (B) is correct c) (A) and (B) are correct d) (A) is correct and (B) is wrong
46. In conventional light sources the ratio of spontaneous emission rate to stimulated emission rate is nearly. a) 1010 b) 1020 c) 105 d) 103
47. Solid state Ruby Laser is a a) Pulsed, three level laser b) pulsed, four level laser c) continuous, three level laser d) continuous four level laser
48. At room temperatures, the threshold current density in heterostructure laser is of the order of
a) 105 Amp / cm2 b) 103 Amp / cm2 c) 102 Amp / cm2 d) 104 Amp / cm2 49. Under population inversion, the number of atoms in the higher energy state is ________ than in the lower
energy state. a) lesser b) larger c) both a) and b) d) none
50. Lasing action can be obtained with extremely small currents by using a) homo structured laser b) hetero structured laser c) buried homo structured laser d) buried homo structured laser
51. At thermal equilibrium in a laser source a) the ratio of the number of stimulated emissions to the number of spontaneous emission is equal to
Einstein coefficient for emission.
b) the ratio of the number of spontaneous to stimulated emissions is given by
−12 kT
h
e πω
c) the ratio of the number of the stimulated emission to spontaneous emission is equal to the ratio of their Einstein coefficients
d) the ratio of probability of stimulated to that of spontaneous emission is equal to 1 52. Yittrium aluminium garnet is a
a) solid state laser source when doped with 3% molybdenum ions b) wonderful superconductor c) very low power laser source d) ferro magnetic material
53. Verify the given statements A) The gas lasers normally exhibit greater coherence than solid state lasers B) ‘The information capacity’ of coherent radiation is tremendously high a) (A) and (B) are wrong b) (A) is wrong or (B) is correct c) (A) is correct, (B) is wrong d) (A), and (B) are correct
54. In optical communication system, the light detector is a) Avalanche photo diode (APD) b) PIN diode c) Photo transistor d) a or b
55. Numerical aperture represents _______ capacity of a optical fibre. a) light gathering b) light dissipation c) heat dissipation d) magnetic lines gathering
56. In optical fibres mode means ________ available for light rays to propagate in the fibre. a) the number of paths b) the number of fibres in optical fibre cable c) the change in R.I. d) none
57. The refractive index of the core is a) Greater than the cladding b) Less than the cladding c) Equal to the cladding d) All the above
58. In step-index fibers the refractive index at the interface of core and cladding changes. a) Abruptly b) Exponentially c) Linearly d) Gradually
59. In graded index fibers, the signals travel in a a) Random manner b) Zig – Zag manner c) Skew manner d) Linear manner
60. Pickout the losses present in the fiber optical communication system a) Distortion losses b) Absorption losses
c) Scattering losses d) All the above 61. If the angle of incidence at the interface of the core and air is exactly equal to acceptance angle then the
ray travels. a) In the core b) In the cladding c) Along the interface d) does not enter into fiber
62. In fiber optical fiber communication systems, electric signals are converted into optical signals by a) Photo detectors b) light emiting diodes c) Solar cell d) all the above
63. The N.A. is related to Refraction induction of core (n1) and refraction induction of clad (n2) . N.A. of the fiber in terms n1 and n2 is
a) n1 – n2 b) 21
)21n2
1(n − c) 21
)1n2(n − d) 21
)2n1(n −
64. For the total internal reflection to take place along the fiber, the essential condition is a) R.I. of core is less than R.I. of clad b) R.I. core is equal to R.I. of clad
c) R.I. of clad is less than R.I. Core d) None 65. Maximum acceptance angle value will be large when
a) n21 – n22 is maximum b) n1 = n2 c) n1 < n2 d) n2 – n1
66. n1 and n2 is 1.68 and 1.44 . The maximum acceptance angle is a) 500 b) 650 c) 600 d) 450
67. Relation between fractional refractive change and N.A. is
a) 21n2
2(NA) b)
2(NA)
212n
c)
12n
NA d)
NA1
2n
68. Exp
−1KT
wh is ____________.
a) The ratio of number of spontaneous to stimulated emissions b) Stimulated to spontaneous emission c) Stimulated emission × spontaneous emission d) None
69. 8. If E2 – E1 = 2.36 ev, the wavelength of radiation is ________ nanometer . a) 750 b) 650 c) 550 d) 450
70. The colour of ruby containing 0.5% Cr, it’s colour is a) Black b) Orange c) Pink d) Yellow
71. In He-Ne laser, the radiation that is emitted is from down ward transition of a) He b) Ne c) both He and Ne d) None
72. The coherence of light is known by the v. visibility of the interference fringes it produces vi. size and nature of the source vii. light intensity of the beam viii. flickering of the light beam
73. The light coming from an ordinary source like a filament bulb is a) coherent, non directional, but powerful
b) non monochromatic, non directional, unpolarized and incoherent c) coherent, non monochromatic, non directional but intense d) non coherent, directional, intense and non monochromatic
74. Cutting and Drilling of metals require high energy sources. The Laser that are used are a) He-Ne Laser b) semi conductor laser c) solid state lasers d) CO2 Laser
75. The semiconductor lasers are not used in a) bar – code reading b) optical communication c) cutting and drilling of metals d) compute printer
76. The purpose of the optical resonator in a laser is a) to provide cover to the active medium b) to provide path for stray atoms c) to provide selectivity of photon states d) to send laser radiation in specified direction
77. In He-Ne lasers a) Oxygen is used to burn and emit light b) the transfer of energy of excitation takes place with by collision of excited helium atoms with neon
atoms c) the helium atoms give the metastable level in between neon energy levels d) the neon atoms under low pressure excite helium atoms
78. Check the correctness of the statements a. The gain of a laser source in the active medium depends on the population difference. b. The purpose of reflectors in the laser is to deflect the photons from the active medium
a) (A) and (B) are wrong b) (A) is wrong and (B) is correct c) (A) and (B) are correct d) (A) is correct and (B) is wrong
c. In conventional light sources the ratio of spontaneous emission rate to stimulated emission rate is nearly.
a) 1010 b) 1020 c) 105 d) 103
79. Solid state Ruby Laser is a a) Pulsed, three level laser b) pulsed, four level laser c) continuous, three level laser d) continuous four level laser
80. At room temperatures, the threshold current density in heterostructure laser is of the order of a) 105 Amp / cm2 b) 103 Amp / cm2 c) 102 Amp / cm2 d) 104 Amp / cm2
a. Under population inversion, the number of atoms in the higher energy state is ________ than in the lower energy state.
a) lesser b) larger c) both a) and b) d) none 50. Lasing action can be obtained with extremely small currents by using
a) homo structured laser b) hetero structured laser c) buried homo structured laser d) buried homo structured laser
81. At thermal equilibrium in a laser source a) the ratio of the number of stimulated emissions to the number of spontaneous emission is equal to
Einstein coefficient for emission.
b) the ratio of the number of spontaneous to stimulated emissions is given by
−12 kT
h
e πω
c) the ratio of the number of the stimulated emission to spontaneous emission is equal to the ratio of their Einstein coefficients
d) the ratio of probability of stimulated to that of spontaneous emission is equal to 1 82. Yittrium aluminium garnet is a
a) solid state laser source when doped with 3% molybdenum ions b) wonderful superconductor c) very low power laser source d) ferro magnetic material
83. Verify the given statements A) The gas lasers normally exhibit greater coherence than solid state lasers B) ‘The information capacity’ of coherent radiation is tremendously high
a) (A) and (B) are wrong b) (A) is wrong or (B) is correct c) (A) is correct, (B) is wrong d) (A), and (B) are correct
84. In optical communication system, the light detector is a) Avalanche photo diode (APD) b) PIN diode c) Photo transistor d) a or b
85. Numerical aperture represents _______ capacity of a optical fibre. a) light gathering b) light dissipation c) heat dissipation d) magnetic lines gathering
86. In optical fibres mode means ________ available for light rays to propagate in the fibre. a) the number of paths b) the number of fibres in optical fibre cable c) the change in R.I. d) none
87. 30. The refractive index of the core is a) Greater than the cladding b) Less than the cladding c) Equal to the cladding d) All the above
88. 31. In step-index fibers the refractive index at the interface of core and cladding changes. a) Abruptly b) Exponentially c) Linearly d) Gradually
89. 32. In graded index fibers, the signals travel in a a) Random manner b) Zig – Zag manner c) Skew manner d) Linear manner
90. 33. Pickout the losses present in the fiber optical communication system a) Distortion losses b) Absorption losses c) Scattering losses d) All the above
91. If the angle of incidence at the interface of the core and air is exactly equal to acceptance angle then the ray travels.
a) In the core b) In the cladding c) Along the interface d) does not enter into fiber
92. In fiber optical fiber communication systems, electric signals are converted into optical signals by a) Photo detectors b) light emiting diodes c) Solar cell d) all the above
93. The N.A. is related to Refraction induction of core (n1) and refraction induction of clad (n2) . N.A. of the fiber in terms n1 and n2 is
a) n1 – n2 b) 21
)21n2
1(n − c) 21
)1n2(n − d) 21
)2n1(n −
94. For the total internal reflection to take place along the fiber, the essential condition is a) R.I. of core is less than R.I. of clad b) R.I. core is equal to R.I. of clad
c) R.I. of clad is less than R.I. Core d) None 95. Maximum acceptance angle value will be large when
a) n21 – n22 is maximum b) n1 = n2 c) n1 < n2 d) n2 – n1
96. n1 and n2 is 1.68 and 1.44 . The maximum acceptance angle is a) 500 b) 650 c) 600 d) 450
97. Relation between fractional refractive change and N.A. is
a) 21n2
2(NA) b)
2(NA)
212n
c)
12n
NA d)
NA1
2n
OBJECTIVE TYPE QUESTIONS UNIT-V
1. The value of x at which Ga As1-x Px changes from direct to indirect band gap material changes when ‘x’ is equal to
a. 0.25 b. 0.35 c. 045 d. 0.55 2. Laser beam that is sent can be detected at long distance of the following property.
a. coherence b. intensity c. monocromacity d. none
3. In the semiconductor laser the reflective plane perpendicular to the P-n Junction forms. a. Injector of electron b. Depletor of carrier c. optical resonator d. Hetero structure laser
4. In the I.R LED the peak wave length emitted by Ga As is a. 8995 A0 b. 9000 A0 c. 9220 A0 d. 9100 A0
5. Frequency of red light, blue light and x-rays are represented by υr υB and υx respectively. Then the band gap energy for Si ( Semiconductor) is nearly equal to a. hυr b. hυB c. hυx d. none
6. Monochromatic means _____________ . a. light containing one wavelengths b. two wavelengths c. no colour d. none 7. The particle size of nano-particles is in the range (a) 1-100 m (b) 1-100 nm (c) 1-100 µm (d) None of he above 8. With fineness of particles, the surface area (a) Increases (b) Decreases (c) Remains same 9. In nanomaterials, densification occurs at (a) Higher temperature (b) Lower temperature (c) Cannot say 10. The prefix nano means _______________________ 11. One nanometer is (a) 1/1,000,000,000 of a meter ( b) 1/1,000,000,000 of a Yard (c) 1/1,000,000 of a meter 12. A human hair measures (a) 50,000 meters (b) 50,000 µm (c) 50,000 nm 13. The smallest things seeable with the unaided human eye are (a) 10,000 nm (b) 10,000 µm (c) 10,000 cm 14. Polymers are sometimes called ____________________ (a) Macromolecules (b) Nanomolecules (c) Micromolecules 15. Any material engineered at the nanoscale to perform a specific task is called ______________ 16. ____________________ are used to turn lights on when the sun goes down. 17. Natural Sensors for biological entities are (a) Biosensors (b) Electromagnetic Sensors (c) Electronic Sensors 18. Sunlight is used to produce chemical or electrical energy in (a) Photovoltaic cells (b) Molecular motors (c) Bio sensors 19. To have good sound effect inside a hall a) the reverberation time has to be as large as possible b) the reverberation time has to be zero. c) the hall should not have any sound absorbing material. d) the reverberation time has to be optimum.
20. Optimum reverbination time for music is a) 0.5 to 1 second b) 0 to 1 second c) 1 to 2 second ` d) above 5 second 21. Sabine’s formula is a) T=0.651V/ΣaS b) T=0. 165V/ΣaS c) T= ΣaS/0.651 V d) T=ΣaS/0.165 V. 22. Two square meter of a fiber board absorbs sound energy as that of unit area of an open window. The
absorption coefficient of fiber board is a)0.50 b)0.2 c)2.0 d)0.0825 23. The walls of a halls built for music concerns should a)amplify sound b)reflect sound c)transmit sound d)absorb sound. 24. which one of the following has maximum absorption coefficient a)marble b) carpet c) human body d) glass 25. which one of the following has minimum absorption coefficient a) felt b) open window c) wooden floor d) glass
