13 Jun 2026

Condensed Matter Physics Standard Problems

Standard competitive exam problems in condensed matter physics with answer key.

condensed-matter solid-state-physics gate-2024 csir-net-2023 jest-2022

These are original standard problems based on frequently tested competitive-exam patterns.

Q: For a simple cubic lattice with lattice constant $a$, the first Brillouin zone boundary along $k_x$ is at
A: $\pm\pi/a$
B: $\pm 2\pi/a$
C: $\pm a/\pi$
D: $\pm 1/a^2$
ANSWER: A
SOURCE: GATE 2024 style
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Q: The Drude electrical conductivity is
A: $ne^2\tau/m$
B: $m/(ne^2\tau)$
C: $ne\tau$
D: $e/(m\tau)$
ANSWER: A
SOURCE: CSIR-NET 2023 style
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Q: A direct band gap semiconductor has
A: valence maximum and conduction minimum at the same $k$
B: no forbidden gap
C: only flat bands
D: zero effective mass
ANSWER: A
SOURCE: JEST 2022 style
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Q: The Debye heat capacity of a 3D solid at low temperature varies as
A: $T$
B: $T^2$
C: $T^3$
D: $e^{-T}$
ANSWER: C
SOURCE: GATE 2021 style
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Q: Bragg diffraction condition is
A: $2d\sin\theta=n\lambda$
B: $d\cos\theta=n\lambda$
C: $2d/\lambda=\sin^2\theta$
D: $d=n\lambda^2$
ANSWER: A
SOURCE: CSIR-NET 2020 style
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Q: In the nearly free electron model, band gaps open primarily at
A: Brillouin zone boundaries
B: the origin only
C: all random wavevectors
D: infinite temperature only
ANSWER: A
SOURCE: GATE style
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Q: The Fermi energy at zero temperature is the energy of
A: the lowest occupied state
B: the highest occupied state
C: every phonon
D: the band gap only
ANSWER: B
SOURCE: CSIR-NET style
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Q: A type-I superconductor shows
A: one critical magnetic field
B: two critical magnetic fields
C: no Meissner effect
D: only paramagnetism
ANSWER: A
SOURCE: JEST style

Problem Sheet Standard MCQs