Selected MCQ

Current Question
In the photoelectric effect, increasing light intensity at fixed frequency above threshold increases:
  • A. Maximum kinetic energy of emitted electrons
  • B. Number of emitted electrons per unit time
  • C. Threshold frequency
  • D. Work function
Correct Answer: B
Explanation:
Intensity raises photon flux, hence emission rate, but not per-electron maximum energy.
Related Question 1
The Doppler effect for light leads to redshift when:
  • A. Source approaches observer
  • B. Source moves away
  • C. Observer moves toward source
  • D. Wavelength decreases
Correct Answer: B
Explanation:
Receding source increases wavelength (redshift).
Related Question 2
Which unit measures frequency?
  • A. Joule
  • B. Watt
  • C. Hertz
  • D. Pascal
Correct Answer: C
Explanation:
Hertz = cycles per second.
Related Question 3
Which phenomenon bends light?
  • A. Reflection
  • B. Refraction
  • C. Diffraction
  • D. Interference
Correct Answer: B
Explanation:
Refraction changes direction in medium.
Related Question 4
Which state has fixed volume but no shape?
  • A. Solid
  • B. Liquid
  • C. Gas
  • D. Plasma
Correct Answer: B
Explanation:
Liquids have definite volume.
Related Question 5
Which constant relates energy and frequency?
  • A. Boltzmann constant
  • B. Planck constant
  • C. Avogadro number
  • D. Gas constant
Correct Answer: B
Explanation:
(E = h\nu).