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Wave behaviour practice questions.

376 exam-style questions on Wave behaviour with answers and explanations. Six real samples below — the full set is free with an account.

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See simple harmonic motion being made

Spin the circle and watch the oscillation draw itself. Then switch on velocity and acceleration to see why a is always opposite to x — the part exam answers get wrong most.

Now try it on a real exam question

  • The amplitude of the small oscillations of a simple pendulum is doubled. What happens to the period of the oscillations?
  • A pendulum clock keeps correct time at sea level. It is taken to the top of a high mountain, where the gravitational field strength is slightly smaller. What happens to the period of its pendulum and to its timekeeping?
  • Which change increases the period of a simple pendulum undergoing small oscillations?

105 more questions on this topic — free with an account.

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Sample questions

In a transverse wave, the oscillations are...

  • exactly parallel to the direction of the energy transfer
  • perpendicular to the direction of energy transfer
  • always in a vacuum
  • always circular

Answer: perpendicular to the direction of energy transfer

Transverse waves oscillate perpendicular to the direction of travel (e.g. light, water surface). Longitudinal waves oscillate parallel (e.g. sound).

When a source of sound moves toward a stationary observer, the observer hears a sound of...

  • lower frequency
  • higher frequency
  • unchanged frequency
  • zero frequency

Answer: higher frequency

This is the Doppler effect: approaching source compresses wavefronts, raising the observed frequency (pitch). Receding lowers it.

A diffraction grating has 500 lines per mm. For light of wavelength 600 nm, what is the first-order diffraction angle?

  • 8.6°
  • 17.5°
  • 36.9°
  • 30.0°

Answer: 17.5°

nλ = d sinθ, d = 1mm/500 = 2.0e-6 m. sinθ = 600e-9/2.0e-6 = 0.30 → θ ≈ 17.5°.

A sound source emitting 500 Hz moves toward a stationary observer at 34 m/s. Speed of sound is 340 m/s. What frequency does the observer hear?

  • 455 Hz
  • 500 Hz
  • 556 Hz
  • 540 Hz

Answer: 556 Hz

f' = f v/(v − vs) = 500 × 340/(340 − 34) = 500 × 340/306 ≈ 556 Hz.

The distance between two adjacent nodes of a standing wave is

  • one wavelength
  • half a wavelength
  • a quarter of a wavelength
  • two wavelengths

Answer: half a wavelength

Adjacent nodes are separated by λ/2; a node-to-antinode distance is λ/4.

A ray of light passes from air into glass. Compared with its value in air, the speed of the light in the glass is

  • higher
  • lower
  • unchanged
  • zero

Answer: lower

Glass is optically denser (higher refractive index), so light travels more slowly in it. The frequency stays the same while the wavelength decreases.

376 Wave behaviour questions — free with an account. Spaced repetition, streaks and full exam simulations included.

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