Lesson 3.6.1.4

3.6.1.4 Forced vibrations and resonance Quiz: AQA Physics, Unit 6

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.6.1.4, Forced vibrations and resonance: 20 multiple choice questions for the AQA Physics (7408), Unit 6: Further mechanics and thermal physics (A-level only), written with Revision Ninja.

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The 20 questions

  1. The frequency at which an oscillator vibrates when displaced and released without a driving force is its:

    • damping frequency
    • resonant period
    • natural frequency
    • driving frequency

  2. Forced vibrations occur when:

    • the system is damped to rest
    • no energy is transferred to the system
    • the system is released from rest
    • an external periodic force drives the oscillator

  3. Resonance occurs when the driving frequency equals:

    • half the natural frequency
    • twice the natural frequency
    • the natural frequency of the system
    • zero

  4. Light damping makes the resonance peak:

    • unchanged in shape
    • eliminated entirely
    • broader and lower
    • sharper and higher

  5. Heavy damping makes the resonance peak:

    • higher and sharper
    • narrower but at the same height
    • lower and broader
    • unchanged

  6. A swing pushed at the right rhythm builds up a large amplitude. This is an example of:

    • resonance
    • damping
    • free oscillation
    • superposition

  7. When the driving frequency is well below the natural frequency, a forced oscillator's amplitude is:

    • exactly zero
    • large and growing without limit
    • small, and it moves roughly in phase with the driver
    • equal to the natural amplitude

  8. A lightly damped system has its natural frequency at 2.0 Hz. At which driving frequency is its amplitude largest?

    • 1.0 Hz
    • 4.0 Hz
    • 2.0 Hz
    • 0.5 Hz

  9. A washing machine vibrates violently at one spin speed. Which explanation is best?

    • The spin frequency is zero at that speed.
    • The machine's damping increases sharply at that speed.
    • The spin frequency matches the machine's natural frequency, causing resonance.
    • The natural frequency of the machine falls to zero at that speed.

  10. Stationary waves on a string are an example of resonance because:

    • waves cancel out at every point of the string
    • the wave travels at zero speed
    • a standing wave builds up when the driving frequency matches a natural mode of the string
    • the string has zero damping

  11. Increasing the damping of a driven system at resonance:

    • reduces the peak amplitude
    • always shifts the resonance to a higher frequency
    • increases the peak amplitude
    • removes the need for a driving force

  12. At resonance in a driven, lightly damped oscillator, the phase difference between the driving force and the displacement is:

    • 0 degrees
    • 45 degrees
    • 180 degrees
    • 90 degrees

  13. A system with natural frequency 4.0 Hz is driven at 4.0 Hz with light damping. Which statement is correct?

    • Its amplitude equals the driving amplitude exactly.
    • Its amplitude is large, limited only by the damping present.
    • Its amplitude is zero because the driving force cancels the natural motion.
    • Its amplitude is smaller than when it is driven at 1.0 Hz.

  14. Once transients have died away, a forced oscillator vibrates at:

    • its natural frequency at all times
    • the driving frequency
    • zero frequency
    • twice the driving frequency

  15. A system oscillates at its natural frequency when set in motion and released without any driving force. This is called:

    • resonant oscillation
    • forced oscillation
    • free oscillation
    • driven oscillation

  16. A driven, lightly damped system has its resonance peak at 3.0 Hz. Which best describes its natural frequency?

    • close to 3.0 Hz, since the peak lies near the natural frequency when damping is light
    • exactly 1.5 Hz, half the peak frequency
    • exactly 6.0 Hz, twice the peak frequency
    • exactly 0 Hz, since the peak is at the driving frequency

  17. A system with natural frequency 5.0 Hz is driven at 2.5 Hz. How does its amplitude compare with driving at 5.0 Hz?

    • Zero, because driving at half the natural frequency cancels the motion
    • Equal, because the driving frequency is a subharmonic
    • Larger, because the driving frequency is half the natural frequency
    • Smaller than at resonance, because the driving frequency is far from the natural frequency

  18. A student says increasing damping always raises the resonant frequency. Which response is best?

    • Incorrect: damping has no effect on any resonance curve.
    • Correct: damping shifts the peak to a higher frequency and sharpens it.
    • Incorrect: damping mainly lowers and broadens the peak, and shifts it slightly lower, not higher.
    • Correct: damping always raises the resonant frequency.

  19. The resonance peak of a driven system is narrower when:

    • damping is greater
    • damping is less
    • the system is heavier and more damped
    • the driving amplitude is doubled

  20. Adding mass to a driven mass-spring system, with the same spring, changes its natural frequency so that the resonant frequency:

    • increases
    • decreases
    • doubles
    • is unchanged

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