Miller indices are obtained by:
A Taking intercepts directly
B Taking reciprocals of intercepts and clearing fractions
C Multiplying intercepts by lattice constants
D Dividing intercepts by 2
Miller indices are reciprocals of fractional intercepts reduced to integers.
The reciprocal lattice of a BCC lattice is:
A BCC
B FCC
C Simple cubic
D HCP
BCC ↔ FCC relationship in reciprocal space.
Brillouin zones are useful for understanding:
A Chemical bonding
B Electrical resistivity
C Electronic band structure
D Magnetic hysteresis
Band theory uses Brillouin zones.
Powder X-ray diffraction patterns are formed because:
A Crystals are perfect
B X-rays are monochromatic
C Crystallites have random orientations
D Only one plane diffracts
Randomly oriented microcrystals give ring patterns.
Einstein model fails at low temperatures because:
A Atoms stop vibrating
B It ignores acoustic modes
C It assumes many frequencies
D It uses classical statistics
Low-frequency phonons are absent in Einstein’s model.
Phonons are quanta of:
A Electromagnetic waves
B Lattice vibrations
C Nuclear vibrations
D Thermal motion only
Phonons describe quantized vibrational modes.
Sommerfeld theory predicts electronic heat capacity varies as:
A T⁰
B √T
C T
D T³
Cv (electronic) ∝ T.
A material behaves as a metal if:
A It has a large band gap
B All bands are filled
C Conduction band is partially filled
D It has low density
Partially filled bands allow conduction.
London penetration depth refers to:
A Electric field penetration
B Thermal wave penetration
C Magnetic field penetration into a superconductor
D Movement of electrons
Magnetic fields decay exponentially inside superconductors.
Donor doping creates:
A Holes
B Extra electrons
C Impurity bands
D Mid-gap states
Donors contribute electrons → n-type semiconductor.
The ideal diode equation assumes:
A No recombination
B No contact potential
C No series resistance
D No doping
Ideal equation neglects series resistance.
Low-voltage Zener diodes have temperature coefficient:
A Positive
B Zero
C Negative
D Variable
Zener effect dominates → negative coefficient.
A BJT in saturation has:
A Both junctions reverse biased
B Base–emitter forward biased, base–collector reverse biased
C Both junctions forward biased
D Only one junction forward biased
Saturation occurs when both junctions conduct.
MOSFET threshold voltage depends on:
A Base current
B Oxide thickness & doping
C Collector resistance
D Frequency only
Vth is influenced by oxide thickness and channel doping.
Positive feedback in amplifiers can cause:
A Rectification
B Attenuation
C Oscillations
D Thermal runaway only
Positive feedback can meet Barkhausen criteria.
Binding energy per nucleon peaks around:
A Carbon
B Oxygen
C Lithium
D Iron
Fe-56 is among the most stable nuclei.
Spontaneous fission is most common in:
A Very light nuclei
B Mid-mass nuclei
C Very heavy nuclei
D Radioactive isotopes only
Large nuclei (A > 230) undergo spontaneous fission.
Half-life is defined as:
A Time for activity to drop to 1/e
B Time for activity to drop to half
C Time for atoms to stop decaying
D Time equals mean life
Standard definition.
Scintillation detectors detect radiation using:
A Magnetic fields
B Gas amplification
C Light emission and PMT detection
D Semiconductor junctions
Incident radiation → photons → PMT output.
Synchrotron radiation is emitted by:
A Neutrons
B Charged particles at rest
C Relativistic charged particles in magnetic fields
D Stationary electrons
Curved relativistic motion emits radiation.
Charged pions (π±) decay mainly into:
A Electron + neutrino
B Photon pairs
C Muon + neutrino
D Proton + antiproton
π⁺ → μ⁺ ν_μ.
G-parity is defined as a combination of charge conjugation and:
A Momentum
B Isospin rotation
C Time reversal
D Baryon number
G = C × isospin rotation.
CPT symmetry is expected to hold in:
A Newtonian mechanics
B Classical electrodynamics
C Local Lorentz-invariant quantum field theories
D Non-relativistic QM
CPT theorem applies to relativistic QFT.
Quark confinement implies:
A Free quarks exist
B Quarks cannot exist alone
C Quarks have infinite mass
D Quarks don’t experience strong force
Only color-neutral hadrons exist.
The (111) plane intercepts the axes at:
A a, b, c
B 2a, 2b, 2c
C a/2, b/2, c/2
D Zero
(111) means intercepts at 1 unit cell length.
Stacking sequence ABCABC corresponds to:
A BCC packing
B FCC packing
C HCP packing
D SC packing
FCC shows ABCABC stacking.
Electron mean free path decreases when:
A Temperature decreases
B Impurities decrease
C Temperature increases
D Lattice becomes stiffer
More phonons increase scattering.
Intrinsic carrier concentration ni depends on:
A Doping only
B Pressure only
C Band gap & temperature
D Crystal symmetry
ni ∝ exp(−Eg/2kT).
A Schottky diode is known for:
A Large reverse breakdown
B Slow switching
C Low forward voltage & fast switching
D Current amplification
Metal–semiconductor junctions switch quickly.
Full-wave bridge rectifier requires:
A 1 diode
B 2 diodes
C 3 diodes
D 4 diodes
Four diodes → full-wave.
Common-base current gain (α) is:
A > 1
B Very small
C Slightly less than 1
D Greater than β
α ≈ 0.98–0.998.
In a depletion-type MOSFET, conduction occurs:
A Only when Vgs > 0
B Only when Vgs < 0
C Even at Vgs = 0
D Never
A channel exists at zero bias.
Flux quantization in superconductors occurs in units of:
A h/e
B 2e/h
C h/2e
D 2h/e
Φ₀ = h/2e due to Cooper pairs.
Peierls transition occurs due to:
A Increased temperature
B Lattice distortion opening band gap
C Gamma irradiation
D Magnetic field suppression
1D metals distort → energy gap at Fermi level.
X-ray diffraction intensities arise from:
A Nuclei only
B Ion cores
C Electron density
D Neutron scattering
X-rays interact with electrons.
Avalanche photodiodes provide:
A No amplification
B Very low sensitivity
C Internal gain
D Gain only at low voltages
Avalanche multiplication amplifies signal.
Slew rate in op-amps refers to:
A Maximum output current
B Rate of change of input
C Maximum rate of change of output
D Maximum gain
Limited by internal compensation.
As v → c, Lorentz factor γ:
A Goes to 1
B Decreases
C Remains constant
D Increases without bound
γ → ∞ as v → c.
Reaction cross-section has units of:
A Energy
B Time
C Area
D Velocity
Units are barns (10⁻²⁸ m²).
Cherenkov radiation is emitted when particle speed exceeds:
A c
B c/2
C c/n
D n/c
v > phase velocity of light in medium.
Charge of strange quark (s) is:
A –1/3
B –2/3
C +1/3
D 0
s quark has charge −1/3 e.
Proton and neutron form a doublet under:
A Baryon symmetry
B Isospin symmetry
C CPT
D Poincaré symmetry
Isospin treats p and n as identical states.
Deep inelastic scattering experiments revealed:
A No internal structure
B Only nuclei have structure
C Quark substructure of nucleons
D New leptons
DIS proved nucleons contain point-like quarks.
Number of color charges in QCD is:
A 1
B 2
C 3
D 6
Colors: red, green, blue.
Bragg peak in proton therapy shows:
A Minimum energy loss
B Constant energy loss
C Maximum energy deposition at end of path
D No significant energy loss
Protons release most energy near stopping point.
For direct band-gap semiconductors, absorption edge corresponds to:
A 2Eg
B Eg
C Eg/2
D No relation
Photon energy ≈ Eg for absorption.
Wiedemann–Franz law connects thermal and electrical conductivity via:
A Resistivity
B Band gap
C Temperature
D Nuclear potential
κ/σT is approximately constant.
High doping in semiconductors may lead to:
A Larger band gap
B No carriers
C Impurity band formation
D Metallic bonding
Overlap of impurity states creates new band.
Photodiode produces current when exposed to photons with energy:
A Less than Eg
B Equal to zero
C Greater than Eg
D Equal to half of Eg
Photons must exceed band gap to create carriers.
Q-value of nuclear reaction is obtained from:
A Charge difference
B Nuclear spin difference
C Mass difference converted to energy
D Temperature
Q = (Δm)c².