When the frequency of the applied force to an oscillating system is equal to its natural frequency , the amplitude of the resulting oscillations increases significantly

Define natural frequency , f 0 .

The frequency of an oscillation when the oscillating system is allowed to oscillate freely

Define driving frequency , f .

The frequency of the forced oscillations , or the frequency of the applied force acting on the system

Under what condition does resonance occur?

When the driving frequency is exactly equal to the natural frequency of the oscillator

At resonance, energy is transferred from the driver to the oscillating system most .......... , so the system transfers the maximum kinetic energy possible.

At resonance, energy is transferred from the driver to the oscillating system most efficiently , so the system transfers the maximum kinetic energy possible.

Give three everyday examples where resonance occurs.

An organ pipe , where air resonates down an air column to set up a stationary wave Glass smashing from a high-pitched sound wave at the right frequency A radio tuned so its electric circuit resonates at the frequency of a specific broadcast

True or False? Resonance only occurs when the driving frequency is greater than the natural frequency.

False. Resonance occurs when the driving frequency is equal to the natural frequency. If the two do not quite match, the amplitude still increases but not to the same maximum extent.

What is the aim of Core Practical 16: Investigating Resonance?

To determine the value of an unknown mass by a graphical method , using the oscillations of known masses on a spring

State the independent and dependent variables for Core Practical 16.

Independent variable = mass (kg) Dependent variable = time period (s) Control variable = the spring / oscillator

On the stand, a clear .......... mark is made about 5 cm below the bottom of the spring so the release point can be judged consistently.

On the stand, a clear fiducial mark is made about 5 cm below the bottom of the spring so the release point can be judged consistently.

State two safety precautions for Core Practical 16.

Clamp the stand to the desk for stability Wear safety glasses in case the spring flies off or snaps Place a cushion or catch-mat in case of falling masses

The reduction in energy and amplitude of oscillations due to resistive forces on the oscillating system

What are the three degrees of damping?

Light damping Critical damping Heavy damping

Describe how a critically damped oscillator behaves when displaced from equilibrium.

It returns to rest at its equilibrium position in the shortest possible time without oscillating (e.g. car suspension systems)

How does a heavily damped system differ from a critically damped one?

A heavily damped system also returns to equilibrium without oscillating , but does so more slowly — it takes a long time to settle (e.g. door dampers)

In a lightly damped system, the amplitude does not decrease linearly — it decays .......... with time.

In a lightly damped system, the amplitude does not decrease linearly — it decays exponentially with time.

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

False. The frequency stays constant as the amplitude decreases, so the time period is unchanged. For example, a child on a swing oscillates once per second regardless of amplitude.

Distinguish between a resistive force and a restoring force .

Resistive force opposes the motion of the oscillator and causes damping Restoring force brings the oscillator back to the equilibrium position

Define a free oscillation .

An oscillation where there are only internal forces (and no external forces) acting and there is no energy input

Define a forced oscillation .

Oscillations acted on by a periodic external force where energy is given in order to sustain the oscillations

At what frequency does a forced oscillation vibrate?

At the same frequency as the external periodic driving force

In a forced oscillation, the periodic driving force does work against the .......... force to replace the energy lost in damping.

In a forced oscillation, the periodic driving force does work against the resistive force to replace the energy lost in damping.

True or False? Anything vibrating in air cannot be a free oscillation.

False. Something vibrating in air is still a free oscillation as long as there are no external forces acting on it — free oscillation does not require a vacuum.

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

A free oscillation — once struck, the fork vibrates at its natural frequency with no external force acting on it

What is a resonance curve ?

A graph of driving frequency f against the amplitude A of the oscillations

On a resonance curve, at what driving frequency is the amplitude a maximum?

At the peak, where the driving frequency equals the natural frequency ( f = f 0 ) — this is resonance

On a resonance curve, when the driving frequency rises above the natural frequency, the amplitude of the oscillations starts to .......... .

On a resonance curve, when the driving frequency rises above the natural frequency, the amplitude of the oscillations starts to decrease .

State three ways increasing the damping changes the resonance curve.

The peak lowers (amplitude at resonance decreases) The peak broadens The peak moves slightly to the left of the natural frequency when heavily damped

True or False? Increasing the damping shifts a system's natural frequency.

False. The natural frequency f 0 stays the same . Increasing damping lowers and broadens the resonance peak and reduces the sharpness of resonance, but does not change f 0 .

What effect does damping have on the sharpness of resonance?

Damping reduces the sharpness of resonance and reduces the amplitude at the resonant frequency

How does increasing the damping of an oscillator affect its amplitude?

Increasing the damping decreases the amplitude of the oscillation

What is a ductile material?

A material that can be stretched a long way — undergoing a large amount of plastic deformation — before it is permanently deformed and snaps. Examples include most metals, particularly copper, gold and silver

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

The kinetic energy of the oscillator is used to deform the material . This energy is transferred into the deformation rather than remaining as oscillation energy, so the amplitude falls

The amplitude of oscillations can be reduced by the plastic deformation of a .......... material.

The amplitude of oscillations can be reduced by the plastic deformation of a ductile material.

How does a climbing rope reduce the force a climber feels during a fall?

It is designed to extend when loaded suddenly , stretching to reduce the amplitude of the oscillation. This provides critical damping , immediately stopping the climber bouncing and reducing the force experienced

True or False? Non-metals are generally good examples of ductile materials.

False. Non-metals are generally not ductile . Most metals — particularly copper, gold and silver — are the ductile materials.

A LevelPhysicsEdexcelFlashcards13. OscillationsResonance

Resonance (Edexcel A Level Physics): Flashcards

Exam code: 9PH0

1/40

0Still learning

Know0

FrontResonance
Define resonance.

Was this flashcard helpful?

Cards in this collection (40)

Define resonance.
When the frequency of the applied force to an oscillating system is equal to its natural frequency, the amplitude of the resulting oscillations increases significantly
Define natural frequency, f₀.
The frequency of an oscillation when the oscillating system is allowed to oscillate freely
Define driving frequency, f.
The frequency of the forced oscillations, or the frequency of the applied force acting on the system
Under what condition does resonance occur?
When the driving frequency is exactly equal to the natural frequency of the oscillator
At resonance, energy is transferred from the driver to the oscillating system most .........., so the system transfers the maximum kinetic energy possible.
At resonance, energy is transferred from the driver to the oscillating system most efficiently, so the system transfers the maximum kinetic energy possible.
Give three everyday examples where resonance occurs.
- An organ pipe, where air resonates down an air column to set up a stationary wave
- Glass smashing from a high-pitched sound wave at the right frequency
- A radio tuned so its electric circuit resonates at the frequency of a specific broadcast
True or False?
Resonance only occurs when the driving frequency is greater than the natural frequency.
False.
Resonance occurs when the driving frequency is equal to the natural frequency. If the two do not quite match, the amplitude still increases but not to the same maximum extent.
What is the aim of Core Practical 16: Investigating Resonance?
To determine the value of an unknown mass by a graphical method, using the oscillations of known masses on a spring
State the independent and dependent variables for Core Practical 16.
- Independent variable = mass (kg)
- Dependent variable = time period (s)
- Control variable = the spring / oscillator
On the stand, a clear .......... mark is made about 5 cm below the bottom of the spring so the release point can be judged consistently.
On the stand, a clear fiducial mark is made about 5 cm below the bottom of the spring so the release point can be judged consistently.
In Core Practical 16, what graph is plotted and what does its gradient equal?
Plot $T^{2}$ (y-axis) against $m$ (x-axis) to get a straight line through the origin, with
$gradient = \frac{4 π^{2}}{k}$
where k is the spring constant
How is the unknown test mass found from the graph of $T^{2}$ against $m$ ?
- Measure T for the test mass and square it to find T²
- Draw a horizontal line from T² to the graph line, then vertically down to the x-axis
- The value of m where it meets the axis is the test mass
- Check the result using digital scales
State two safety precautions for Core Practical 16.
- Clamp the stand to the desk for stability
- Wear safety glasses in case the spring flies off or snaps
- Place a cushion or catch-mat in case of falling masses
True or False?
A graph of $T$ against $m$ gives a straight line through the origin.
False.
A graph of $T^{2}$ against $m$ gives a straight line through the origin, because $T^{2} = m (\frac{4 π^{2}}{k})$
Define damping.
The reduction in energy and amplitude of oscillations due to resistive forces on the oscillating system
What are the three degrees of damping?
- Light damping
- Critical damping
- Heavy damping
Describe how a critically damped oscillator behaves when displaced from equilibrium.
It returns to rest at its equilibrium position in the shortest possible time without oscillating (e.g. car suspension systems)
How does a heavily damped system differ from a critically damped one?
A heavily damped system also returns to equilibrium without oscillating, but does so more slowly — it takes a long time to settle (e.g. door dampers)
In a lightly damped system, the amplitude does not decrease linearly — it decays .......... with time.
In a lightly damped system, the amplitude does not decrease linearly — it decays exponentially with time.
True or False?
As a damped oscillation loses amplitude, its frequency also decreases.
False.
The frequency stays constant as the amplitude decreases, so the time period is unchanged. For example, a child on a swing oscillates once per second regardless of amplitude.
Distinguish between a resistive force and a restoring force.
- Resistive force opposes the motion of the oscillator and causes damping
- Restoring force brings the oscillator back to the equilibrium position
Define a free oscillation.
An oscillation where there are only internal forces (and no external forces) acting and there is no energy input
Define a forced oscillation.
Oscillations acted on by a periodic external force where energy is given in order to sustain the oscillations
At what frequency does a free oscillation always vibrate?
At its natural frequency
At what frequency does a forced oscillation vibrate?
At the same frequency as the external periodic driving force
In a forced oscillation, the periodic driving force does work against the .......... force to replace the energy lost in damping.
In a forced oscillation, the periodic driving force does work against the resistive force to replace the energy lost in damping.
True or False?
Anything vibrating in air cannot be a free oscillation.
False.
Something vibrating in air is still a free oscillation as long as there are no external forces acting on it — free oscillation does not require a vacuum.
Is striking a tuning fork a free or forced oscillation, and why?
A free oscillation — once struck, the fork vibrates at its natural frequency with no external force acting on it
What is a resonance curve?
A graph of driving frequency f against the amplitude A of the oscillations
On a resonance curve, at what driving frequency is the amplitude a maximum?
At the peak, where the driving frequency equals the natural frequency (f = f₀) — this is resonance
On a resonance curve, when the driving frequency rises above the natural frequency, the amplitude of the oscillations starts to ...........
On a resonance curve, when the driving frequency rises above the natural frequency, the amplitude of the oscillations starts to decrease.
State three ways increasing the damping changes the resonance curve.
- The peak lowers (amplitude at resonance decreases)
- The peak broadens
- The peak moves slightly to the left of the natural frequency when heavily damped
True or False?
Increasing the damping shifts a system's natural frequency.
False.
The natural frequency f₀ stays the same. Increasing damping lowers and broadens the resonance peak and reduces the sharpness of resonance, but does not change f₀.
What effect does damping have on the sharpness of resonance?
Damping reduces the sharpness of resonance and reduces the amplitude at the resonant frequency
How does increasing the damping of an oscillator affect its amplitude?
Increasing the damping decreases the amplitude of the oscillation
What is a ductile material?
A material that can be stretched a long way — undergoing a large amount of plastic deformation — before it is permanently deformed and snaps. Examples include most metals, particularly copper, gold and silver
How does the plastic deformation of a ductile material reduce the amplitude of oscillations?
The kinetic energy of the oscillator is used to deform the material. This energy is transferred into the deformation rather than remaining as oscillation energy, so the amplitude falls
The amplitude of oscillations can be reduced by the plastic deformation of a .......... material.
The amplitude of oscillations can be reduced by the plastic deformation of a ductile material.
How does a climbing rope reduce the force a climber feels during a fall?
It is designed to extend when loaded suddenly, stretching to reduce the amplitude of the oscillation. This provides critical damping, immediately stopping the climber bouncing and reducing the force experienced
True or False?
Non-metals are generally good examples of ductile materials.
False.
Non-metals are generally not ductile. Most metals — particularly copper, gold and silver — are the ductile materials.

Sign up to unlock flashcards

By signing up you agree to our Terms and Privacy Policy

Previous:Simple Harmonic Motion