1. The residue of the complex function f(z) = z cos(1/z) at its essential singularity z = 0 is:
(a) 1
(b) 0
(c) -1/2
(d) 1/2
Answer: (c)
2. If A and B are two Hermitian operators, then the operator i[A, B] is always:
(a) Anti-Hermitian
(b) Hermitian
(c) Unitary
(d) Orthogonal
Answer: (b)
3. The density of states for a free electron gas in two dimensions (2D) is proportional to energy E as:
(a) E1/2
(b) E
(c) E0 (Constant, independent of E)
(d) E-1/2
Answer: (c)
4. In the anomalous Zeeman effect, the transition between the 2P1/2 and 2S1/2 states splits into how many components?
(a) 2
(b) 3
(c) 4
(d) 6
Answer: (c)
5. For a dynamical system, if the Hamiltonian H does not contain time 't' explicitly, then:
(a) Total momentum is conserved
(b) The Hamiltonian H is a constant of motion
(c) Only kinetic energy is conserved
(d) The generalized coordinates are cyclic
Answer: (b)
6. Liénard-Wiechert potentials are used in electrodynamics to describe the scalar and vector potentials of:
(a) A stationary charge distribution
(b) A steadily carrying current wire
(c) A moving point charge
(d) A static magnetic dipole
Answer: (c)
7. The eigenvalues of a unitary matrix are always:
(a) Real and positive
(b) Purely imaginary
(c) Of unit modulus (|λ| = 1)
(d) Zero
Answer: (c)
8. In the nuclear shell model, which of the following represents a "doubly magic" heavy nucleus?
(a) 56Fe
(b) 208Pb
(c) 235U
(d) 197Au
Answer: (b)
9. The phase velocity (vp) of an electromagnetic wave propagating in a good conductor relates to its angular frequency (ω) as:
(a) vp ∝ ω
(b) vp ∝ √ω
(c) vp ∝ 1/ω
(d) vp ∝ 1/√ω
Answer: (b)
10. The fundamental logic gate corresponding to the Boolean algebraic expression Y = (A · B)' is the:
(a) NOR gate
(b) XOR gate
(c) AND gate
(d) NAND gate
Answer: (d)
11. According to the Third Law of Thermodynamics, the entropy of a perfect crystal at absolute zero temperature (0 K) is:
(a) Infinite
(b) Maximum
(c) Zero
(d) Dependent on the material's mass
Answer: (c)
12. For a quantum mechanical particle confined in a one-dimensional box of length L, if the length of the box is suddenly halved (L/2), the ground state energy E1 becomes:
(a) E1 / 2
(b) 2 E1
(c) 4 E1
(d) E1 / 4
Answer: (c)
13. The Landé g-factor for a pure orbital atomic state (where total spin S = 0) is precisely:
(a) 0
(b) 1
(c) 2
(d) 3/2
Answer: (b)
14. In Solid State Physics, the volume of the primitive unit cell for a Body-Centered Cubic (BCC) lattice with lattice parameter 'a' is:
(a) a3
(b) a3 / 2
(c) a3 / 4
(d) a3 / 8
Answer: (b)
15. A semiconductor sample has an equal number of electrons and holes, but the mobility of electrons is significantly higher. The expected Hall coefficient will be:
(a) Zero
(b) Positive
(c) Negative
(d) Infinite
Answer: (c)
16. The divergence of the curl of any continuous, differentiable vector field F (∇ · (∇ × F)) is always equal to:
(a) ∇2F
(b) 1
(c) 0
(d) ∇(∇ · F)
Answer: (c)
17. The isospin quantum number (I) assigned to a pion (π meson) triplet is:
(a) 0
(b) 1/2
(c) 1
(d) 3/2
Answer: (c)
18. The specific heat of a superconductor precisely at its critical transition temperature (Tc) exhibits a:
(a) Smooth exponential drop
(b) Divergence to infinity
(c) Discontinuous jump
(d) Constant value
Answer: (c)
19. Which of the following parameters remains invariant under a Lorentz transformation?
(a) Length
(b) Time interval
(c) Total energy
(d) Proper time
Answer: (d)
20. The trace (sum of diagonal elements) of the Pauli spin matrix σx is:
(a) 1
(b) 2
(c) 0
(d) -1
Answer: (c)
21. The Miller indices (h k l) of a crystal plane that is parallel to the y and z axes, and cuts the x-axis at a distance 'a', are:
(a) (0 1 1)
(b) (1 1 1)
(c) (1 0 0)
(d) (0 0 1)
Answer: (c)
22. The group velocity (vg) and phase velocity (vp) for a non-relativistic free particle are mathematically related by:
(a) vg = vp
(b) vg = 2vp
(c) vg = vp / 2
(d) vg × vp = c2
Answer: (b)
23. The selection rule for a pure vibrational transition of a quantum harmonic oscillator is:
(a) Δv = 0
(b) Δv = ±1
(c) Δv = ±2
(d) Δv = 0, ±1
Answer: (b)
24. In the liquid drop model of the nucleus, the surface energy term is proportional to the mass number A as:
(a) A
(b) A1/3
(c) A2/3
(d) A-1/3
Answer: (c)
25. The speed of an electromagnetic wave in a dielectric medium with permittivity ε and permeability μ is given by:
(a) 1 / √(εμ)
(b) √(ε/μ)
(c) εμ
(d) 1 / (εμ)
Answer: (a)
26. The rest mass of a photon is theoretically considered to be:
(a) 9.1 × 10-31 kg
(b) 1.6 × 10-27 kg
(c) Dependent on its frequency
(d) Zero
Answer: (d)
27. A coordinate 'q' is said to be cyclic if it does not appear explicitly in the Lagrangian. The corresponding conjugate momentum 'p' is then:
(a) Zero
(b) A constant of motion
(c) Exponentially decaying
(d) Equal to the kinetic energy
Answer: (b)
28. The number of independent components of a completely symmetric second-rank tensor in 3-dimensional space is:
(a) 3
(b) 6
(c) 9
(d) 12
Answer: (b)
29. The fundamental interaction responsible for the beta decay of a free neutron into a proton, an electron, and an antineutrino is the:
(a) Strong interaction
(b) Electromagnetic interaction
(c) Gravitational interaction
(d) Weak interaction
Answer: (d)
30. The first Born approximation in scattering theory gives highly accurate results specifically for:
(a) Low incident energies and strong scattering potentials
(b) High incident energies and weak scattering potentials
(c) Resonance scattering only
(d) Extremely long-range forces like gravity
Answer: (b)
31. In the context of the WKB approximation, the connection formulas are required primarily because:
(a) The potential energy approaches infinity
(b) The approximation fails at classical turning points where p(x) = 0
(c) The wave function becomes strictly zero everywhere
(d) The particle's energy exceeds the potential barrier
Answer: (b)
32. Fermi's Golden Rule for the transition rate in time-dependent perturbation theory indicates that the transition probability per unit time is proportional to:
(a) The density of final states
(b) The inverse of the density of final states
(c) The square of the density of final states
(d) Independent of the density of final states
Answer: (a)
33. For a one-dimensional quantum harmonic oscillator, the commutator [a, a†] of the annihilation operator (a) and creation operator (a†) is exactly:
(a) 0
(b) 1
(c) -1
(d) iℏ
Answer: (b)
34. According to the Larmor formula, the total power radiated by a non-relativistic point charge 'q' accelerating with an acceleration 'a' is proportional to:
(a) a
(b) a2
(c) 1/a
(d) a3
Answer: (b)
35. In a hollow rectangular waveguide of dimensions a × b (where a > b), the dominant transverse electric (TE) mode of propagation is:
(a) TE00
(b) TE01
(c) TE10
(d) TE11
Answer: (c)
36. The skin depth (δ) of an electromagnetic wave in a conducting medium with conductivity σ and permeability μ varies with angular frequency ω as:
(a) ω
(b) 1/ω
(c) 1/√ω
(d) √ω
Answer: (c)
37. The fundamental condition for Bose-Einstein condensation to occur in an ideal Bose gas is that the chemical potential (μ) must:
(a) Be positive and highly large
(b) Be exactly equal to the ground state energy
(c) Approach negative infinity
(d) Fluctuate randomly with temperature
Answer: (b)
38. At absolute zero temperature (T = 0 K), the Fermi-Dirac distribution function for an energy state exactly equal to the Fermi energy (E = EF) yields a probability of:
(a) 1
(b) 0
(c) 1/2
(d) Undefined
Answer: (c)
39. In the canonical ensemble, the partition function Z is a sum over all accessible microstates. The probability Pi of finding the system in a specific microstate with energy Ei is given by:
(a) exp(-Ei/kT) / Z
(b) Z / exp(-Ei/kT)
(c) exp(Ei/kT) / Z
(d) 1 / (Z exp(-Ei/kT))
Answer: (a)
40. Bloch's theorem states that the wave function of an electron in a periodic crystal lattice potential can be written as ψ(r) = eik·r uk(r), where uk(r) is:
(a) A Gaussian envelope function
(b) A function with the same periodicity as the crystal lattice
(c) A purely exponentially decaying function
(d) A constant value everywhere in space
Answer: (b)
41. According to the Debye model of specific heat for solids, at very low temperatures, the lattice specific heat capacity (Cv) is proportional to:
(a) T
(b) T2
(c) T3
(d) e-1/T
Answer: (c)
42. In a purely p-type semiconductor, the Hall coefficient (RH) is mathematically expected to be:
(a) Zero
(b) Exactly equal to 1
(c) Negative
(d) Positive
Answer: (d)
43. The phenomenon where a superconductor perfectly expels all magnetic flux from its interior when cooled below its critical temperature is known as:
(a) The Josephson effect
(b) The Meissner effect
(c) The Hall effect
(d) The Peltier effect
Answer: (b)
44. In the semi-empirical mass formula (liquid drop model), the pairing energy term δ contributes positively to the binding energy for nuclei that are:
(a) Even-Z, Even-N
(b) Odd-Z, Odd-N
(c) Even-Z, Odd-N
(d) Odd-Z, Even-N
Answer: (a)
45. Which of the following fundamental conservation laws is strictly violated in weak nuclear interactions (such as beta decay)?
(a) Conservation of electric charge
(b) Conservation of baryon number
(c) Conservation of parity
(d) Conservation of total angular momentum
Answer: (c)
46. According to the quark model, a neutron is composed of which combination of constituent quarks?
(a) uud (two up, one down)
(b) udd (one up, two down)
(c) sss (three strange)
(d) ud̄ (one up, one anti-down)
Answer: (b)
47. A radioactive sample has a half-life of 10 days. The fraction of the original active nuclei remaining after 30 days will be:
(a) 1/3
(b) 1/4
(c) 1/8
(d) 1/9
Answer: (c)
48. In an ideal operational amplifier connected in an inverting amplifier configuration, if the input resistor is R1 and the feedback resistor is Rf, the closed-loop voltage gain (Av) is:
(a) 1 + (Rf / R1)
(b) -(Rf / R1)
(c) -(R1 / Rf)
(d) 1 + (R1 / Rf)
Answer: (b)
49. Applying Boolean algebra, the expression A + (A · B) simplifies directly to:
(a) B
(b) A · B
(c) A
(d) 1
Answer: (c)
50. A J-K flip-flop will systematically operate in its "toggle" mode (output state flips on every clock pulse) only when its inputs are:
(a) J = 0, K = 0
(b) J = 1, K = 0
(c) J = 0, K = 1
(d) J = 1, K = 1
Answer: (d)
51. The Zener breakdown mechanism in a heavily doped p-n junction diode fundamentally occurs due to:
(a) Avalanche multiplication of carriers
(b) Quantum tunneling of electrons across the narrow depletion region
(c) Thermal runaway heating the junction
(d) Recombination of electron-hole pairs
Answer: (b)
52. In Raman scattering spectroscopy, the spectral lines shifted to frequencies lower than the incident excitation frequency are historically called:
(a) Anti-Stokes lines
(b) Rayleigh lines
(c) Stokes lines
(d) Lyman lines
Answer: (c)
53. The strict electric dipole selection rule for the change in the orbital angular momentum quantum number (Δl) during an atomic transition is:
(a) Δl = 0
(b) Δl = ±1
(c) Δl = ±2
(d) Δl = 0, ±1
Answer: (b)
54. The fine structure splitting observed in the energy levels of the hydrogen atom is predominantly caused by the physical phenomenon of:
(a) Hyperfine coupling
(b) The external magnetic field (Zeeman effect)
(c) Spin-orbit coupling and relativistic corrections
(d) Finite nuclear mass effects
Answer: (c)
55. For a rigid diatomic molecule treated as a quantum rotator, the spacing in energy between adjacent pure rotational energy levels J and J+1:
(a) Remains constant for all values of J
(b) Increases linearly as J increases
(c) Decreases exponentially as J increases
(d) Is exactly zero
Answer: (b)
56. In order to achieve Light Amplification by Stimulated Emission of Radiation (LASER), which of the following non-equilibrium states must be established in the active medium?
(a) Absolute zero temperature
(b) Perfect thermal equilibrium
(c) Population inversion
(d) Maximum spontaneous emission
Answer: (c)
57. In the general theory of relativity, the covariant derivative of the metric tensor gμν vanishes identically everywhere. This fundamental property is known as:
(a) Bianchi identity
(b) Metric compatibility
(c) Lorentz invariance
(d) Equivalence principle
Answer: (b)
58. According to the Bohr-van Leeuwen theorem, the classical calculation of thermal average magnetization for an electron gas in thermal equilibrium yields a result that is exactly:
(a) Infinite
(b) Proportional to the external field
(c) Zero
(d) Negative (diamagnetic)
Answer: (c)
59. A fundamental property of the Pauli spin matrices (σx, σy, σz) is that their determinant is always:
(a) 1
(b) -1
(c) 0
(d) i
Answer: (b)
60. For a system executing simple harmonic motion in one dimension, the phase space trajectory representing its dynamics maps out a mathematically perfect:
(a) Hyperbola
(b) Parabola
(c) Ellipse
(d) Straight line
Answer: (c)
61. In complex analysis, the function f(z) = ln(z) has a branch point at:
(a) z = 1
(b) z = i
(c) z = 0 and z = ∞
(d) It has no branch points
Answer: (c)
62. In quantum scattering theory, the partial wave analysis is most useful and practically applicable when the incident particle energy is:
(a) Extremely high
(b) Low, such that only the s-wave (l=0) contributes significantly
(c) Equal to the rest mass energy
(d) Infinite
Answer: (b)
63. The magnetic flux (Φ) passing through a closed superconducting ring is strictly quantized. The fundamental quantum of magnetic flux (Φ0) is given by:
(a) h / e
(b) h / 2e
(c) 2h / e
(d) ℏ / e
Answer: (b)
64. According to the extreme single-particle nuclear shell model, the expected ground state spin and parity (Jπ) of the 13C nucleus (Z=6, N=7) is:
(a) (1/2)-
(b) (3/2)-
(c) (1/2)+
(d) (5/2)+
Answer: (a)
65. The Common Mode Rejection Ratio (CMRR) of a differential amplifier is mathematically defined as the ratio of:
(a) Differential mode gain to common mode gain (Ad / Ac)
(b) Common mode gain to differential mode gain (Ac / Ad)
(c) Input impedance to output impedance
(d) Slew rate to bandwidth
Answer: (a)
66. In electromagnetism, a gauge transformation of the potentials A → A + ∇χ and V → V - ∂χ/∂t leaves which of the following invariant?
(a) Only the electric field E
(b) Only the magnetic field B
(c) Both the electric field E and the magnetic field B
(d) Neither E nor B
Answer: (c)
67. The grand partition function relates to the grand potential (Ω) through the fundamental thermodynamic equation:
(a) Ω = -kT ln(Z)
(b) Ω = kT ln(Z)
(c) Ω = -Z ln(kT)
(d) Ω = 1 / ln(Z)
Answer: (a)
68. The moment of inertia tensor of a completely rigid, spherically symmetric body (like a uniform solid sphere) is mathematically represented by a matrix that is:
(a) Anti-symmetric
(b) A scalar multiple of the identity matrix
(c) Traceless
(d) Singular (determinant is zero)
Answer: (b)
69. The parity operator P^ is a Hermitian and unitary operator. Its possible eigenvalues are:
(a) 0 and 1
(b) +1 and -1
(c) +i and -i
(d) All real numbers
Answer: (b)
70. In particle physics, Kaons (K-mesons) are notable because they possess a non-zero value of which quantum number?
(a) Baryon number
(b) Lepton number
(c) Strangeness
(d) Charm
Answer: (c)
71. In a one-dimensional diatomic crystal lattice, the optical phonon branch differs from the acoustic branch primarily because, at the Brillouin zone center (k=0), the optical branch frequency:
(a) Drops exactly to zero
(b) Approaches infinity
(c) Has a non-zero, finite maximum value
(d) Becomes purely imaginary
Answer: (c)
72. In tensor calculus, the Kronecker delta δij is formally classified as a:
(a) Contravariant tensor of rank 2
(b) Covariant tensor of rank 2
(c) Mixed tensor of rank 2
(d) Scalar of rank 0
Answer: (c)
73. For a rectangular waveguide of dimensions 'a' (width) and 'b' (height) where a > b, the cutoff frequency (fc) for the dominant TE10 mode is given by:
(a) c / (2a)
(b) c / (2b)
(c) c / (a+b)
(d) 2c / a
Answer: (a)
74. The coherence time (τc) of a laser beam is physically related to its spectral linewidth (Δν) by the approximate relation:
(a) τc ≈ Δν
(b) τc ≈ 1 / Δν
(c) τc ≈ (Δν)2
(d) τc ≈ √Δν
Answer: (b)
75. An ideal Atwood machine consists of two masses connected by an inextensible massless string over a frictionless, massless pulley. The number of degrees of freedom for this system is:
(a) 1
(b) 2
(c) 3
(d) 4
Answer: (a)
76. For a degenerate free electron gas in 3D, the Fermi momentum (pF) depends on the electron number density (n) as:
(a) n
(b) n1/2
(c) n1/3
(d) n2/3
Answer: (c)
77. Clebsch-Gordan coefficients arise in quantum mechanics during the mathematical process of:
(a) Solving the radial part of the hydrogen atom
(b) Adding two angular momenta
(c) Calculating time-dependent transition probabilities
(d) Normalizing wave functions in infinite wells
Answer: (b)
78. Compared to TTL (Transistor-Transistor Logic), the CMOS (Complementary Metal-Oxide-Semiconductor) logic family is best known for its:
(a) Much faster switching speeds
(b) High static power dissipation
(c) Extremely low static power consumption
(d) Inability to act as a logic gate
Answer: (c)
79. In nuclear gamma decay, a transition from an initial state of spin-parity 2+ to a final ground state of 0+ can proceed exclusively via which multipole radiation?
(a) Electric dipole (E1)
(b) Magnetic dipole (M1)
(c) Electric quadrupole (E2)
(d) Magnetic quadrupole (M2)
Answer: (c)
80. In solid-state band theory, the effective mass (m*) of an electron is inversely proportional to the:
(a) Electron's charge
(b) First derivative of energy with respect to wave vector (dE/dk)
(c) Second derivative of energy with respect to wave vector (d2E/dk2)
(d) Lattice constant of the crystal
Answer: (c)
81. A quarter-wave plate introduces a phase difference between the ordinary and extraordinary rays equal to:
(a) π / 4
(b) π / 2
(c) π
(d) 2π
Answer: (b)
82. The Paschen-Back effect occurs when an atom is placed in an external magnetic field that is:
(a) Extremely weak compared to internal spin-orbit coupling
(b) Modulating at a high radio frequency
(c) Extremely strong, disrupting the internal L-S coupling
(d) Strictly zero
Answer: (c)
83. The Bessel functions Jn(x) form an orthogonal set of functions with respect to a weight function w(x) equal to:
(a) 1
(b) x
(c) e-x
(d) 1/x
Answer: (b)
84. In the special theory of relativity, the standard Minkowski spacetime metric tensor ημν (using the + - - - convention) has a determinant equal to:
(a) +1
(b) 0
(c) -1
(d) -4
Answer: (c)
85. Coherent states in quantum mechanics, heavily used in quantum optics, are specifically defined as the exact eigenstates of the:
(a) Hamiltonian operator
(b) Position operator
(c) Annihilation operator
(d) Creation operator
Answer: (c)
86. In a Bipolar Junction Transistor (BJT), the Early effect (base-width modulation) causes the collector current to:
(a) Decrease as collector-base voltage increases
(b) Increase slightly as collector-base voltage increases
(c) Drop abruptly to zero
(d) Remain absolutely constant regardless of voltage
Answer: (b)
87. A key operational advantage of a Proportional Counter over a Geiger-Muller (GM) counter is its ability to:
(a) Operate at much higher applied voltages
(b) Discriminate between different types of incident radiation based on energy
(c) Detect neutrinos easily
(d) Work without a quenching gas
Answer: (b)
88. One of Maxwell's thermodynamic relations states that (∂S / ∂V)T is exactly equal to:
(a) (∂P / ∂T)V
(b) -(∂P / ∂T)V
(c) (∂T / ∂P)S
(d) (∂V / ∂T)P
Answer: (a)
89. The Curie-Weiss law for the magnetic susceptibility (χ) of a ferromagnetic material above its Curie temperature (TC) is given by:
(a) χ = C / T
(b) χ = C / (T - TC)
(c) χ = C (T - TC)
(d) χ = C / T2
Answer: (b)
90. The average power radiated by an oscillating electric dipole is proportional to the driving angular frequency ω raised to the power of:
(a) 2
(b) 3
(c) 4
(d) -2
Answer: (c)
91. In mathematical physics, the Green's function G(x, x') for a linear differential operator L mathematically represents the impulse response to a:
(a) Step function
(b) Sinusoidal source
(c) Dirac delta function point source δ(x - x')
(d) Gaussian distribution
Answer: (c)
92. The quantum mechanical operator for the z-component of orbital angular momentum, Lz, expressed in spherical polar coordinates is:
(a) -iℏ (∂/∂r)
(b) -iℏ (∂/∂θ)
(c) -iℏ (∂/∂φ)
(d) -iℏ r (∂/∂r)
Answer: (c)
93. The London penetration depth (λL) in a superconductor dictates how far a magnetic field penetrates into the material. It depends on the number density of superconducting electrons (ns) as:
(a) λL ∝ ns
(b) λL ∝ 1 / ns
(c) λL ∝ 1 / √ns
(d) λL ∝ √ns
Answer: (c)
94. The Mössbauer effect refers to the phenomenon of:
(a) Recoil-free emission and absorption of gamma rays by atomic nuclei bound in a solid crystal
(b) Splitting of nuclear energy levels in a strong magnetic field
(c) Emission of electrons due to high-energy gamma ray bombardment
(d) Spontaneous fission of superheavy elements
Answer: (a)
95. In a circular waveguide of radius 'a', the dominant mode of propagation (the one with the lowest cutoff frequency) is the:
(a) TM01 mode
(b) TE01 mode
(c) TE11 mode
(d) TM11 mode
Answer: (c)
96. Maxwell's thermodynamic relations can be derived from the exact differentials of thermodynamic potentials. The relation (∂T / ∂V)S = -(∂P / ∂S)V is derived from the:
(a) Internal Energy (U)
(b) Helmholtz Free Energy (F)
(c) Enthalpy (H)
(d) Gibbs Free Energy (G)
Answer: (a)
97. The maximum rate of change of the output voltage of an operational amplifier in response to a step input is defined as its:
(a) Gain-bandwidth product
(b) Slew rate
(c) Common-mode rejection ratio
(d) Unity-gain frequency
Answer: (b)
98. In classical mechanics, the Euler-Lagrange equations are invariant under the addition of a specific type of term to the Lagrangian. This term must be:
(a) A constant total energy term
(b) A total time derivative of any function of coordinates and time, dF(q,t)/dt
(c) A purely velocity-dependent dissipative function
(d) A harmonic oscillator potential
Answer: (b)
99. The theoretical particle mediating the strong force between quarks is called the:
(a) Photon
(b) W Boson
(c) Gluon
(d) Pion
Answer: (c)
100. The Franck-Condon principle in molecular physics is based on the assumption that during an electronic transition:
(a) The nuclear internuclear distance and velocity remain practically unchanged
(b) The molecule must dissociate completely
(c) The vibrational quantum number must change by exactly ±1
(d) The total spin of the molecule must invert
Answer: (a)
101. The Laplace transform of the Heaviside unit step function u(t-a) is:
(a) e-as / s
(b) eas / s
(c) 1 / (s-a)
(d) 1 / (s+a)
Answer: (a)
102. In first-order time-independent perturbation theory, the first-order correction to the energy of the n-th state (En(1)) due to a perturbation H' is calculated as:
(a) <ψn | H' | ψn>
(b) Σm≠n |<ψm | H' | ψn>|2 / (En - Em)
(c) <ψn | (H')2 | ψn>
(d) 0
Answer: (a)
103. The shape of the first Brillouin zone for a two-dimensional square lattice with lattice constant 'a' is a:
(a) Hexagon
(b) Square of side 2π/a
(c) Circle of radius π/a
(d) Rectangle
Answer: (b)
104. The process of internal conversion in a nucleus involves the:
(a) Conversion of a neutron into a proton
(b) Emission of an orbital electron instead of a gamma-ray photon during de-excitation
(c) Absorption of an external photon to create an electron-positron pair
(d) Capture of a K-shell electron by the nucleus
Answer: (b)
105. Liénard-Wiechert potentials are "retarded" potentials, meaning the potential at position r and time t depends on the state of the source charge at a prior time tr. The retardation time delay is given by:
(a) |r| / c
(b) |r - r'(tr)| / c
(c) c / |r|
(d) 0
Answer: (b)
106. In a system exhibiting Bose-Einstein condensation, the fraction of particles in the ground state (N0/N) varies with absolute temperature T (for T < Tc) according to:
(a) 1 - (T/Tc)3/2
(b) 1 - (T/Tc)2
(c) (T/Tc)3/2
(d) e-T/Tc
Answer: (a)
107. In digital electronics, a Karnaugh map (K-map) is primarily utilized for:
(a) Designing active band-pass filters
(b) Systematically minimizing Boolean logic expressions
(c) Converting analog signals to digital signals
(d) Generating clock pulses
Answer: (b)
108. The Euler equations of motion for a rigid body simplify significantly if the coordinate axes are chosen to be the:
(a) Axes of the laboratory frame
(b) Axes passing through the center of mass parallel to the laboratory frame
(c) Principal axes of inertia of the body
(d) Axes tangential to the body's surface
Answer: (c)
109. The CP (Charge Conjugation and Parity) violation, which helps explain the matter-antimatter asymmetry in the universe, was first experimentally observed in the decay of:
(a) Protons
(b) Neutral Kaons
(c) Muons
(d) Neutrons
Answer: (b)
110. In atomic physics, the Lamb shift experimentally demonstrated a minute energy difference between the 22S1/2 and 22P1/2 levels of hydrogen. This shift is successfully explained by:
(a) Simple Bohr theory
(b) The Dirac equation alone
(c) Quantum Electrodynamics (QED) via vacuum polarization and electron self-energy
(d) The finite size of the proton
Answer: (c)
111. In tensor calculus, if Ai is a contravariant vector and Bj is a covariant vector, their inner product AiBi forms a:
(a) Tensor of rank 2
(b) Vector (tensor of rank 1)
(c) Scalar invariant (tensor of rank 0)
(d) Matrix
Answer: (c)
112. According to the WKB approximation, the transmission coefficient (T) for a particle of mass m and energy E tunneling through a wide, smooth potential barrier V(x) (where V(x) > E) is roughly proportional to:
(a) exp [ -(2/ℏ) ∫ √(2m(E - V(x))) dx ]
(b) exp [ -(2/ℏ) ∫ √(2m(V(x) - E)) dx ]
(c) exp [ (2/ℏ) ∫ √(2m(V(x) - E)) dx ]
(d) cos [ (1/ℏ) ∫ √(2m(E - V(x))) dx ]
Answer: (b)
113. In a semiconductor where both electrons and holes contribute to conduction, the net Hall coefficient RH vanishes to zero if:
(a) n = p (intrinsic condition)
(b) nμe = pμh
(c) nμe2 = pμh2
(d) μe = μh
Answer: (c)
114. The Q-value of a nuclear reaction is defined as the difference between the sum of the rest mass energies of the initial reactants and the final products. An exothermic reaction has a Q-value that is:
(a) Zero
(b) Negative
(c) Positive
(d) Imaginary
Answer: (c)
115. According to the Fresnel equations, when unpolarized light reflects off a dielectric surface at Brewster's angle, the reflected light is:
(a) Completely unpolarized
(b) Circularly polarized
(c) Linearly polarized parallel to the plane of incidence
(d) Linearly polarized perpendicular to the plane of incidence
Answer: (d)
116. The single-particle partition function Z for a classical one-dimensional harmonic oscillator of frequency ν at temperature T is given by:
(a) kT / hν
(b) hν / kT
(c) exp(-hν / kT)
(d) 1 / (1 - exp(-hν / kT))
Answer: (a)
117. An RC phase-shift oscillator generally uses three identical RC high-pass sections in its feedback network. For the circuit to oscillate, the amplifier must provide a phase shift of:
(a) 0°
(b) 90°
(c) 180°
(d) 360°
Answer: (c)
118. In the theory of small oscillations of a conservative system around a point of stable equilibrium, the eigenvalues of the secular determinant directly correspond to the system's:
(a) Normal coordinates
(b) Total mechanical energies
(c) Squares of the normal mode angular frequencies (ω2)
(d) Damping coefficients
Answer: (c)
119. In Quantum Electrodynamics (QED), Møller scattering describes the fundamental interaction between:
(a) An electron and a positron (e- e+ → e- e+)
(b) Two electrons (e- e- → e- e-)
(c) An electron and a photon (e- γ → e- γ)
(d) A photon and a photon (γ γ → γ γ)
Answer: (b)
120. In the rotational Raman spectrum of a diatomic molecule, the transition selection rules (ΔJ = ±2) lead to the formation of S-branch and O-branch lines. The spacing between adjacent S-branch lines is:
(a) 2B
(b) 4B
(c) 6B
(d) 8B
Answer: (b)
121. In complex analysis, if a function f(z) has a pole of order 'm' at z = a, then the residue at this pole can be evaluated using the formula:
(a) limz→a (z-a)m f(z)
(b) limz→a [1/(m-1)!] (dm-1/dzm-1) [ (z-a)m f(z) ]
(c) limz→a [1/m!] (dm/dzm) [ (z-a) f(z) ]
(d) limz→a (d/dz) [ (z-a)m f(z) ]
Answer: (b)
122. If F(s) is the Laplace transform of f(t), then the Laplace transform of the derivative f'(t) is given by:
(a) s F(s) - f(0)
(b) F(s) / s
(c) s F(s) + f(0)
(d) dF(s)/ds
Answer: (a)
123. For a canonical transformation in classical mechanics, the fundamental Poisson brackets of the new coordinates (Q, P) must satisfy:
(a) [Qi, Qj] = 1, [Pi, Pj] = 1
(b) [Qi, Pj] = 0
(c) [Qi, Pj] = δij
(d) [Qi, Pj] = -1
Answer: (c)
124. The metric tensor gμν for flat three-dimensional space in spherical polar coordinates (r, θ, φ) is a diagonal matrix with elements:
(a) (1, 1, 1)
(b) (1, r2, r2sin2θ)
(c) (1, r, r sinθ)
(d) (1, r2, sin2θ)
Answer: (b)
125. For a system of two identical fermions, the total wave function (including both spatial and spin parts) must be:
(a) Symmetric under particle exchange
(b) Antisymmetric under particle exchange
(c) Spherically symmetric
(d) Independent of particle spin
Answer: (b)
126. In the WKB approximation, the solutions near the classical turning points (where E = V(x)) diverge. To connect the oscillatory and exponentially decaying solutions across a turning point, one typically uses:
(a) Hermite polynomials
(b) Legendre polynomials
(c) Airy functions
(d) Bessel functions
Answer: (c)
127. The Clebsch-Gordan coefficients, which arise when adding two angular momenta j1 and j2 to form a total angular momentum J, are non-zero only if:
(a) J = j1 + j2 only
(b) |j1 - j2| ≤ J ≤ j1 + j2
(c) J = |j1 - j2| only
(d) J is an integer
Answer: (b)
128. Retarded potentials in electrodynamics imply that the electromagnetic field at a point 'r' and time 't' depends on the source charge/current distribution at:
(a) The same time 't'
(b) A future time t + (|r-r'|/c)
(c) A past time t - (|r-r'|/c)
(d) Time t = 0
Answer: (c)
129. The time-averaged Poynting vector <S> representing the angular distribution of radiation from an oscillating electric dipole is proportional to:
(a) sin(θ)
(b) cos2(θ)
(c) sin2(θ)
(d) 1 / cos(θ)
Answer: (c)
130. A TM (Transverse Magnetic) mode propagating in a hollow metallic cylindrical waveguide has the defining characteristic that:
(a) The longitudinal electric field Ez = 0
(b) The longitudinal magnetic field Bz = 0
(c) Both Ez = 0 and Bz = 0
(d) The transverse fields are zero
Answer: (b)
131. In statistical mechanics, the Fermi-Dirac distribution function f(E) becomes exactly a step function (f(E)=1 for E<EF and f(E)=0 for E>EF) at what temperature?
(a) T = ∞
(b) T = TF (Fermi temperature)
(c) T = 0 K
(d) T = 300 K
Answer: (c)
132. The critical temperature Tc for Bose-Einstein condensation of an ideal, non-interacting Bose gas depends on the particle number density 'n' as:
(a) n1/3
(b) n2/3
(c) n
(d) Independent of n
Answer: (b)
133. The canonical partition function Z for N identical, indistinguishable classical non-interacting particles is related to the single-particle partition function Z1 by:
(a) Z = Z1N
(b) Z = N * Z1
(c) Z = Z1N / N!
(d) Z = N! * Z1N
Answer: (c)
134. In the Kronig-Penney model of a 1D crystal lattice, energy band gaps appear specifically at the boundaries of the Brillouin zones, which occur when the wave vector 'k' equals:
(a) 0
(b) ± nπ / a (where n = 1, 2, 3...)
(c) ± π / 2a
(d) ± 2nπa
Answer: (b)
135. In BCS theory, the coherence length (ξ) of a superconductor roughly represents:
(a) The depth to which a magnetic field can penetrate
(b) The spatial extent of a Cooper pair
(c) The mean free path of normal electrons
(d) The distance between adjacent lattice ions
Answer: (b)
136. The Hall coefficient RH of a material is experimentally found to be inversely proportional to the:
(a) Applied magnetic field
(b) Applied electric field
(c) Charge carrier density
(d) Sample thickness
Answer: (c)
137. According to the liquid drop model, the plot of atomic masses of isobars (nuclei with the same A) against their atomic number Z yields a curve that is approximately a:
(a) Straight line
(b) Parabola
(c) Hyperbola
(d) Sine wave
Answer: (b)
138. The legendary "Wu experiment" involving the beta decay of Cobalt-60 atoms aligned in a magnetic field definitively proved that:
(a) Energy is not conserved in weak interactions
(b) Parity is maximally violated in weak interactions
(c) Neutrinos have mass
(d) The strong force is charge-independent
Answer: (b)
139. The Gell-Mann-Nishijima formula relates the electric charge (Q) of a hadron to its isospin component (I3), baryon number (B), and strangeness (S). The formula is:
(a) Q = I3 + (B + S)/2
(b) Q = I3 + B + S
(c) Q = 2I3 + B + S
(d) Q = I3 + (B - S)/2
Answer: (a)
140. In Quantum Chromodynamics (QCD), the fundamental vertex represents the interaction between:
(a) An electron, a positron, and a photon
(b) A quark, an antiquark, and a gluon
(c) A proton, a neutron, and a pion
(d) A W boson and a lepton pair
Answer: (b)
141. The basic building block Feynman diagram in Quantum Electrodynamics (QED) always consists of a vertex joining:
(a) Two straight fermion lines and one wavy photon line
(b) Three wavy photon lines
(c) Two wavy photon lines and one straight fermion line
(d) Three straight fermion lines
Answer: (a)
142. The Landé g-factor for an atomic state with total angular momentum J, orbital angular momentum L, and spin S is given by g = 1 + [J(J+1) + S(S+1) - L(L+1)] / [2J(J+1)]. For a 2S1/2 state, 'g' equals:
(a) 1
(b) 2
(c) 3/2
(d) 0
Answer: (b)
143. The first-order Stark effect (linear splitting of energy levels in an electric field) is non-zero in the hydrogen atom only for states where:
(a) The principal quantum number n = 1
(b) There is an accidental degeneracy of states with opposite parity (e.g., 2s and 2p)
(c) The electron spin is parallel to the external field
(d) The orbital angular momentum L = 0
Answer: (b)
144. In the vibration-rotation spectrum of a diatomic molecule, the spectral lines corresponding to transitions where the rotational quantum number changes by ΔJ = -1 constitute the:
(a) P-branch
(b) Q-branch
(c) R-branch
(d) S-branch
Answer: (a)
145. An operational amplifier (Op-Amp) connected as a differentiator circuit utilizes:
(a) A resistor in the input and a capacitor in the feedback path
(b) A capacitor in the input and a resistor in the feedback path
(c) Capacitors in both the input and feedback paths
(d) An inductor in the feedback path
Answer: (b)
146. In an astable multivibrator built using a 555 Timer IC with external resistors RA, RB, and timing capacitor C, the charging time constant is proportional to:
(a) (RA + RB) C
(b) RB C
(c) RA C
(d) (RA + 2RB) C
Answer: (a)
147. A Karnaugh map (K-map) is a graphical tool used primarily to simplify Boolean algebra expressions in the form of:
(a) Sum of Products (SOP) or Product of Sums (POS)
(b) Sequential state diagrams
(c) Analog voltage levels
(d) Fourier series expansions
Answer: (a)
148. The "magic numbers" in nuclear physics (2, 8, 20, 28, 50, 82, 126) represent nuclei with exceptionally high stability. These numbers are successfully explained by adding which interaction to the nuclear shell model?
(a) Coulomb repulsion
(b) Strong spin-orbit (L·S) coupling
(c) Weak interaction
(d) Tensor force
Answer: (b)
149. The Maxwell thermodynamic relation derived directly from the exact differential of Enthalpy (dH = T dS + V dP) is:
(a) (∂T / ∂P)S = (∂V / ∂S)P
(b) (∂S / ∂V)T = (∂P / ∂T)V
(c) (∂T / ∂V)S = -(∂P / ∂S)V
(d) (∂S / ∂P)T = -(∂V / ∂T)P
Answer: (a)
150. A particle of mass 'm' is moving in a 3D harmonic oscillator potential V(r) = (1/2)mω2r2. The degree of degeneracy of its first excited energy state is:
(a) 1 (Non-degenerate)
(b) 3
(c) 6
(d) 9
Answer: (b)
