Define natural frequency .

The natural frequency is the frequency at which an oscillating system oscillates when it is allowed to oscillate freely, with no external driving force.

Resonance occurs when the frequency of an applied (driving) force equals the natural frequency of an oscillating system, causing the amplitude of oscillations to increase significantly to a maximum.

Why is energy transferred most efficiently from the driver to the oscillator at resonance?

At resonance the driving frequency equals the natural frequency, so the driver transfers maximum kinetic energy to the oscillating system, most efficiently.

Give three examples of systems that demonstrate resonance.

An organ pipe , where air resonates to set up a stationary wave in the pipe Glass smashing from a sound wave at the glass's natural frequency A radio circuit tuned to resonate at the frequency of a broadcast

True or False? If the driving frequency does not exactly equal the natural frequency, the amplitude of oscillations does not increase at all.

False. The amplitude still increases as the driving frequency approaches the natural frequency, just not to the same extent as at resonance, where the increase is greatest.

State the aim of Core Practical 16: Investigating Resonance.

To determine the value of an unknown mass by a graphical method, using the resonant frequencies of oscillation of known masses.

State the independent and dependent variables in Core Practical 16.

Independent variable = mass (kg); dependent variable = time period (s).

Define the control variable in Core Practical 16.

The spring (oscillator) used, which must be kept the same throughout the experiment.

Describe how the time period for each mass is measured accurately in this practical.

Time is measured for ten oscillations , repeated three times in total for each mass, then the average is taken and divided by ten to give one time period.

Why is the fiducial mark repositioned after each 100 g mass is added?

The spring extends further with each additional mass, so the fiducial mark must be moved to stay 5 cm below the new, lower position of the spring.

To find an unknown test mass, a horizontal line is drawn from its T 2 value to the graph line, then a .......... line is drawn down to the x-axis to read off the mass.

To find an unknown test mass, a horizontal line is drawn from its T 2 value to the graph line, then a vertical line is drawn down to the x-axis to read off the mass.

True or False? In Core Practical 16, the independent variable is the time period and the dependent variable is the mass.

False. The independent variable is mass (the quantity deliberately changed); the dependent variable is time period (the quantity measured).

Damping is the reduction in energy and amplitude of oscillations due to resistive forces acting on the oscillating system.

Define critical damping .

Critical damping returns a displaced oscillator to equilibrium in the shortest possible time without oscillating.

What happens to the amplitude of a lightly damped oscillator over time, and how does its frequency change?

Amplitude decreases exponentially with time, while the frequency (and time period) of oscillation remains constant .

Give one everyday example each of critical damping and heavy damping.

Critical damping : car suspension systems Heavy damping : door dampers (to prevent slamming)

In a critically damped system, what does the displacement-time graph look like once the oscillator reaches equilibrium?

The graph becomes a horizontal line at zero displacement for the remaining time — no oscillation occurs.

In a heavily damped system, the oscillator returns to equilibrium .......... than in a critically damped system, without oscillating.

In a heavily damped system, the oscillator returns to equilibrium more slowly than in a critically damped system, without oscillating.

True or False? As a lightly damped oscillator loses amplitude, its frequency also decreases.

False. The frequency of a damped oscillator stays constant as the amplitude decreases; only the amplitude decreases (exponentially, for light damping).

Define free oscillation .

An oscillation with only internal forces acting (no external forces) and no energy input .

Define forced oscillation .

An oscillation acted on by a periodic external (driving) force , where energy is given in order to sustain the oscillations.

At what frequency does a free vibration always oscillate?

At its natural (resonant) frequency .

What is the purpose of the periodic driving force in a forced oscillation?

It does work against the resistive force , replacing the energy lost to damping so the oscillations are sustained.

Is striking a tuning fork a free or a forced oscillation, and why?

A free oscillation — once struck, it vibrates at its natural frequency with no external forces acting on it.

In a forced oscillation, the oscillator vibrates at the same frequency as the external force producing it, known as the .......... frequency.

In a forced oscillation, the oscillator vibrates at the same frequency as the external force producing it, known as the driving frequency.

True or False? A forced oscillation always vibrates at the natural frequency of the oscillator.

False. A forced oscillation vibrates at the driving frequency of the external periodic force, which only equals the natural frequency at resonance.

Define a resonance curve .

A graph of driving frequency, f , against amplitude, A , of oscillations.

Describe how amplitude changes as driving frequency increases from below to above the natural frequency.

When f f 0 , amplitude decreases

What three effects does increasing damping have on the shape of a resonance curve?

The peak amplitude decreases (curve lowers) The peak broadens The peak shifts slightly to the left of the natural frequency

Does the natural frequency of an oscillator change when damping is increased?

No — the natural frequency, f 0 , stays the same regardless of the degree of damping.

As damping increases, the resonance peak .......... and its amplitude decreases.

As damping increases, the resonance peak broadens and its amplitude decreases.

True or False? Increasing damping shifts the resonance peak slightly to the right of the natural frequency.

False. Increasing damping shifts the resonance peak slightly to the left of the natural frequency (when heavily damped).

How are damping and amplitude related in an oscillating system?

They are inversely proportional — as damping increases, amplitude decreases.

A ductile material can undergo a large amount of plastic deformation, stretching significantly before it snaps. Most metals, such as copper, gold and silver, are ductile.

Define plastic deformation .

A permanent change in the shape of a material that remains after the deforming force is removed.

How does plastic deformation of a ductile material reduce the amplitude of oscillations?

Kinetic energy from the oscillator is used to deform the material , transferring energy away from the oscillation and reducing its amplitude.

Why is a climbing rope designed to stretch when a climber falls onto it?

The stretching reduces the amplitude of the resulting oscillation and provides critical damping , immediately stopping the climber bouncing and reducing the force (and injury) experienced.

A ductile material, such as copper, undergoes plastic deformation which transfers kinetic energy from an oscillator, .......... the amplitude of its oscillations.

A ductile material, such as copper, undergoes plastic deformation which transfers kinetic energy from an oscillator, reducing the amplitude of its oscillations.

True or False? Non-metals are generally more ductile than metals.

False. Most metals (e.g. copper, gold, silver) are ductile; non-metals are generally not ductile .

International A Level (IAL)PhysicsEdexcelFlashcards5. Thermodynamics, Radiation, Oscillations & CosmologyResonance

Resonance (Edexcel International A Level (IAL) Physics): Flashcards

Exam code: YPH11

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Cards in this collection (42)

Define natural frequency.
The natural frequency is the frequency at which an oscillating system oscillates when it is allowed to oscillate freely, with no external driving force.
Define resonance.
Resonance occurs when the frequency of an applied (driving) force equals the natural frequency of an oscillating system, causing the amplitude of oscillations to increase significantly to a maximum.
What name is given to the frequency of the periodic force applied to an oscillating system?
The driving frequency.
Why is energy transferred most efficiently from the driver to the oscillator at resonance?
At resonance the driving frequency equals the natural frequency, so the driver transfers maximum kinetic energy to the oscillating system, most efficiently.
Give three examples of systems that demonstrate resonance.
- An organ pipe, where air resonates to set up a stationary wave in the pipe
- Glass smashing from a sound wave at the glass's natural frequency
- A radio circuit tuned to resonate at the frequency of a broadcast
When the driving frequency is exactly equal to the natural frequency, $f = f_{0}$ , the oscillator vibrates with its .......... amplitude.
When the driving frequency is exactly equal to the natural frequency, $f = f_{0}$ , the oscillator vibrates with its maximum amplitude.
True or False?
If the driving frequency does not exactly equal the natural frequency, the amplitude of oscillations does not increase at all.
False.
The amplitude still increases as the driving frequency approaches the natural frequency, just not to the same extent as at resonance, where the increase is greatest.
State the aim of Core Practical 16: Investigating Resonance.
To determine the value of an unknown mass by a graphical method, using the resonant frequencies of oscillation of known masses.
State the independent and dependent variables in Core Practical 16.
Independent variable = mass (kg); dependent variable = time period (s).
Define the control variable in Core Practical 16.
The spring (oscillator) used, which must be kept the same throughout the experiment.
Describe how the time period for each mass is measured accurately in this practical.
Time is measured for ten oscillations, repeated three times in total for each mass, then the average is taken and divided by ten to give one time period.
Why is the fiducial mark repositioned after each 100 g mass is added?
The spring extends further with each additional mass, so the fiducial mark must be moved to stay 5 cm below the new, lower position of the spring.
What does the gradient of the T² against m graph equal?
$gradient = \frac{4 π^{2}}{k}$
where k is the spring constant.
To find an unknown test mass, a horizontal line is drawn from its T² value to the graph line, then a .......... line is drawn down to the x-axis to read off the mass.
To find an unknown test mass, a horizontal line is drawn from its T² value to the graph line, then a vertical line is drawn down to the x-axis to read off the mass.
True or False?
In Core Practical 16, the independent variable is the time period and the dependent variable is the mass.
False.
The independent variable is mass (the quantity deliberately changed); the dependent variable is time period (the quantity measured).
Define damping.
Damping is the reduction in energy and amplitude of oscillations due to resistive forces acting on the oscillating system.
Define critical damping.
Critical damping returns a displaced oscillator to equilibrium in the shortest possible time without oscillating.
What happens to the amplitude of a lightly damped oscillator over time, and how does its frequency change?
Amplitude decreases exponentially with time, while the frequency (and time period) of oscillation remains constant.
Give one everyday example each of critical damping and heavy damping.
- Critical damping: car suspension systems
- Heavy damping: door dampers (to prevent slamming)
In a critically damped system, what does the displacement-time graph look like once the oscillator reaches equilibrium?
The graph becomes a horizontal line at zero displacement for the remaining time — no oscillation occurs.
In a heavily damped system, the oscillator returns to equilibrium .......... than in a critically damped system, without oscillating.
In a heavily damped system, the oscillator returns to equilibrium more slowly than in a critically damped system, without oscillating.
True or False?
As a lightly damped oscillator loses amplitude, its frequency also decreases.
False.
The frequency of a damped oscillator stays constant as the amplitude decreases; only the amplitude decreases (exponentially, for light damping).
Define free oscillation.
An oscillation with only internal forces acting (no external forces) and no energy input.
Define forced oscillation.
An oscillation acted on by a periodic external (driving) force, where energy is given in order to sustain the oscillations.
At what frequency does a free vibration always oscillate?
At its natural (resonant) frequency.
What is the purpose of the periodic driving force in a forced oscillation?
It does work against the resistive force, replacing the energy lost to damping so the oscillations are sustained.
Is striking a tuning fork a free or a forced oscillation, and why?
A free oscillation — once struck, it vibrates at its natural frequency with no external forces acting on it.
In a forced oscillation, the oscillator vibrates at the same frequency as the external force producing it, known as the .......... frequency.
In a forced oscillation, the oscillator vibrates at the same frequency as the external force producing it, known as the driving frequency.
True or False?
A forced oscillation always vibrates at the natural frequency of the oscillator.
False.
A forced oscillation vibrates at the driving frequency of the external periodic force, which only equals the natural frequency at resonance.
Define a resonance curve.
A graph of driving frequency, f, against amplitude, A, of oscillations.
Describe how amplitude changes as driving frequency increases from below to above the natural frequency.
- When f < f₀, amplitude increases
- At f = f₀, amplitude is at its maximum (resonance)
- When f > f₀, amplitude decreases
What three effects does increasing damping have on the shape of a resonance curve?
- The peak amplitude decreases (curve lowers)
- The peak broadens
- The peak shifts slightly to the left of the natural frequency
Does the natural frequency of an oscillator change when damping is increased?
No — the natural frequency, f₀, stays the same regardless of the degree of damping.
As damping increases, the resonance peak .......... and its amplitude decreases.
As damping increases, the resonance peak broadens and its amplitude decreases.
True or False?
Increasing damping shifts the resonance peak slightly to the right of the natural frequency.
False.
Increasing damping shifts the resonance peak slightly to the left of the natural frequency (when heavily damped).
How are damping and amplitude related in an oscillating system?
They are inversely proportional — as damping increases, amplitude decreases.
Define ductile.
A ductile material can undergo a large amount of plastic deformation, stretching significantly before it snaps. Most metals, such as copper, gold and silver, are ductile.
Define plastic deformation.
A permanent change in the shape of a material that remains after the deforming force is removed.
How does plastic deformation of a ductile material reduce the amplitude of oscillations?
Kinetic energy from the oscillator is used to deform the material, transferring energy away from the oscillation and reducing its amplitude.
Why is a climbing rope designed to stretch when a climber falls onto it?
The stretching reduces the amplitude of the resulting oscillation and provides critical damping, immediately stopping the climber bouncing and reducing the force (and injury) experienced.
A ductile material, such as copper, undergoes plastic deformation which transfers kinetic energy from an oscillator, .......... the amplitude of its oscillations.
A ductile material, such as copper, undergoes plastic deformation which transfers kinetic energy from an oscillator, reducing the amplitude of its oscillations.
True or False?
Non-metals are generally more ductile than metals.
False.
Most metals (e.g. copper, gold, silver) are ductile; non-metals are generally not ductile.

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