Selected MCQ

Current Question
In quantum mechanics, the commutator ([x,p]) equals:
  • A. 0
  • B. (i\hbar)
  • C. (-i\hbar)
  • D. (\hbar^2)
Correct Answer: B
Explanation:
Position and momentum operators satisfy ([x,p]=i\hbar).
Related Question 1
In a Hilbert space formulation of quantum mechanics, physical states are represented by:
  • A. Real numbers
  • B. Vectors up to a global phase
  • C. Scalars only
  • D. Matrices only
Correct Answer: B
Explanation:
States are rays in Hilbert space, invariant under global phase.
Related Question 2
In quantum mechanics, expectation value of an observable corresponds to:
  • A. Most probable value
  • B. Average measurement over many identical systems
  • C. Minimum energy
  • D. Maximum probability
Correct Answer: B
Explanation:
Expectation value is statistical mean of repeated measurements.
Related Question 3
In quantum mechanics, eigenvalues of an operator correspond to:
  • A. Allowed measurement outcomes
  • B. Wave amplitudes
  • C. Probabilities directly
  • D. Coordinates only
Correct Answer: A
Explanation:
Observables yield eigenvalues upon measurement.
Related Question 4
Which quantum number determines orbital shape?
  • A. Principal
  • B. Azimuthal
  • C. Magnetic
  • D. Spin
Correct Answer: B
Explanation:
Azimuthal quantum number defines orbital geometry.
Related Question 5
In quantum electrodynamics, the interaction between charged particles is mediated by:
  • A. Gluons
  • B. Photons
  • C. Gravitons
  • D. W bosons
Correct Answer: B
Explanation:
Electromagnetic interactions occur via exchange of virtual photons.