Lesson 13.2.1

13.2.1 Resonance, free and forced oscillations Quiz: Pearson Edexcel Physics, Unit 13

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 13.2.1, Resonance, free and forced oscillations: 20 multiple choice questions for the Pearson Edexcel Physics (9PH0), Unit 13: Oscillations, written with Revision Ninja.

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The 20 questions

  1. What is free oscillation?

    • Oscillation with no restoring force acting on the object at any point in its motion.
    • Oscillation at the system's natural frequency, with no external periodic driver.
    • Oscillation that increases in amplitude without any limit as time passes on.
    • Oscillation at a frequency set entirely by an external driving force that is applied.

  2. When does resonance occur?

    • When the driving frequency is exactly twice the natural frequency of the system only.
    • When the driving frequency equals the natural frequency, giving maximum amplitude.
    • When the system has no damping at any frequency, so energy is never lost at all.
    • When the driving force is reduced to zero, so the system oscillates on its own freely.

  3. In forced oscillations, at what frequency does the system oscillate in the steady state?

    • Zero, since the driving force stops it.
    • Its natural frequency only.
    • Twice its natural frequency.
    • The driving frequency.

  4. What effect does increasing damping have on the resonance peak?

    • It has no effect on the peak.
    • It moves the peak to a much higher frequency and keeps it sharp.
    • It reduces the peak amplitude and broadens the peak.
    • It increases the peak amplitude.

  5. Which everyday example shows the danger of resonance?

    • A stone dropped into still water, which spreads ripples that die away over the surface.
    • Soldiers breaking step, since marching at a bridge's natural frequency causes resonance.
    • A pendulum clock keeping steady time, since its escapement holds the frequency constant.
    • A guitar string plucked gently with a finger, which then sounds quietly for a while.

  6. A mass of 0.20 kg on a spring of stiffness 50 N m^-1 has natural frequency (1/2 π) sqrt(k/m). What is this frequency?

    • 2.5 Hz
    • 0.16 Hz
    • 15.8 Hz
    • 0.40 Hz

  7. A system has natural frequency 2.5 Hz. It is driven at 5.0 Hz. Compared with its amplitude at resonance, the amplitude is

    • larger
    • infinite
    • the same
    • smaller

  8. A spring of stiffness 40 N m^-1 has resonant frequency 2.0 Hz with an unknown mass. What is the unknown mass?

    • 0.25 kg
    • 1.0 kg
    • 4.0 kg
    • 0.10 kg

  9. If the mass on a spring is quadrupled, what happens to its natural frequency?

    • It is unchanged.
    • It quarters.
    • It halves.
    • It doubles.

  10. An oscillator's amplitude falls by a factor of 0.8 each cycle. Starting at 10 cm, what is the amplitude after 3 cycles?

    • 1.0 cm
    • 2.0 cm
    • 8.0 cm
    • about 5.1 cm

  11. Why does a forced oscillator with light damping have a very sharp resonance peak?

    • Light damping removes the restoring force.
    • Little energy is removed per cycle, so the amplitude can build up strongly near the natural frequency.
    • Light damping adds energy to the system at every cycle.
    • Light damping makes the natural frequency change to the driving frequency.

  12. A forced oscillator is driven well above its natural frequency. What happens to its amplitude as the driving frequency increases further?

    • It falls towards zero.
    • It rises without limit.
    • It doubles for each increase in frequency.
    • It stays at the resonant value.

  13. Why do car shock absorbers contain damping?

    • Damping makes the car's natural frequency increase without limit.
    • Damping keeps the car's frequency exactly equal to the bumps.
    • Damping adds energy so the car bounces higher on bumps.
    • Damping removes energy, so resonant bouncing when driven over bumps is limited.

  14. What is the natural frequency of a system?

    • The frequency at which it is damped the most.
    • The number of oscillations it makes per metre.
    • The frequency of the driving force that gives resonance.
    • The frequency at which it oscillates when free from external driving forces.

  15. Which pairing describes a forced oscillation?

    • A child pushed on a swing at regular intervals.
    • A pendulum clock with no external input.
    • A ball dropped onto a hard floor once.
    • A swing left to move on its own after one push.

  16. What is the effect of driving a system exactly at its natural frequency with little damping?

    • The system's frequency changes to zero.
    • The system stops oscillating.
    • The amplitude becomes zero.
    • The amplitude becomes large, which is resonance.

  17. Which statement about free and forced oscillations is correct?

    • Both kinds of oscillation occur only at the natural frequency, whatever the system is doing.
    • Free oscillation is at the natural frequency; forced oscillation is at the driving frequency.
    • Forced oscillations always occur at the natural frequency of the system, whatever the driver.
    • Free oscillations are always driven by an external force that keeps them going steadily.

  18. A system is driven at 4 Hz, its natural frequency, with light damping. What is the steady-state frequency of oscillation?

    • 0 Hz
    • 2 Hz
    • 4 Hz
    • 8 Hz

  19. What is the natural frequency of a 2.0 kg mass on a spring of stiffness 8.0 N m^-1?

    • 0.16 Hz
    • 2.0 Hz
    • 1.6 Hz
    • 0.32 Hz

  20. With increasing damping, what happens to the peak on an amplitude against driving frequency graph?

    • The peak becomes infinitely sharp.
    • The peak height rises and the peak becomes narrower.
    • The peak height falls and the peak becomes broader.
    • The peak moves to zero frequency.

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