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Physics paper 2 AQA > Waves > Flashcards

Waves Flashcards

1
Q

What are waves?

A

Repeated vibrations of energy transfer

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2
Q

How is energy transferred?

A

By waves knocking neighbouring particles

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3
Q

What is a transverse wave?

A

Waves where points along the wave vibrate perpendicular to the direction of energy transfer

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4
Q

For a transverse wave

A

The energy transfer is in the same direction as the motion
They transfer energy but not particles of the medium
They move through liquids and solids but not gas
Some can travel through a medium (EM WAVES)

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5
Q

Examples of TRANSVERSE waves

A
  • Ripples on the surface of the water
  • Vibrations on a guitar string
  • S waves
  • EM waves
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6
Q

What are longitudinal waves?

A

Waves were the points along the wave vibrate parrallel to the direction of energy transfer

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7
Q

Properties of a longitudinal wave

A
  • Energy transfer is in the same direction as motion
  • Transfer energy but not particles of a medium
  • CAN moves through liquids solids and gas
  • They CANT travel through a vacuum as there are no particles
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8
Q

Examples of longitudinal waves

A
  • Sound waves
  • P waves
  • Pressure waves
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9
Q

What is amplitude, wave length, wave frequency and time period?

A

Amplitude= Distance from the undisturbed position of the wave to the peak or trough - METRES
Wavelength= The distance from one point on a wave to the same point on the next wave - METRES (Symbol is lambada)
Wave frequency= The amount of waves that pass a point in one second - HERTZ
Time period= The time take for one wave to pass a point - SECONDS

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10
Q

Equation for wave speed

A

Wave speed = Frequency x Time

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11
Q

What do transverse waves have?

A

Peaks and troughs

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12
Q

What do longitudinal waves have?

A

Rarefactions and compressions

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13
Q

How are sounds waves transmitted?

A

Longitudinal waves work by the molecules vibrating and knocking into vibrating particles/molecules.
The more molecules that are present the more faster the wave can transfer energy

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14
Q

In what medium do sound waves travel fastest?

A

In solids and slowest in gases

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15
Q

Refraction of sound

A

When sound waves travel from a denser medium to a less dense medium their:
Wavelength increases
Frequency stays the same
Velocity increases

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16
Q

What is reflection?

A

When a wave hits a boundry between two media and doesnt pass through

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17
Q

Rule for the angles of incidence and reflection?

A

The angle of incidence=angle of reflection

18
Q

Reflection on flat surfaces

A

Flat surfaces are much smoother so the stronger the reflected ray

19
Q

Reflection on rough surfaces

A

Least reflective, because the light scatters in all direction

20
Q

What do opaque surfaces reflect?

A

Opaque surfaces reflect the light that isnt absorbed by the material
The electrons will absorb the light energy then reemit it as a reflective wave

21
Q

What is transmission?

A

When a wave passes through a substance

22
Q

What happens when a wave is transmitted through a material?

A

It is partially absorbed so the transmitted wave has a smaller amplitude

23
Q

What is absorbtion?

A

When the energy is transferred from the wave to the particles of a substance
Waves can be partially or completely absorbed

24
Q

When will light be absorbed by a material?

A

When the frequency of the wave matches the levels of the electrons

25
Q

How do sound waves travel through solids

A

Sound waves are vibrations of air particles
When a sound wave comes in contact with a solid, these vibrating air particles are transferred to the solid
The compressions and rarefactions cause changes in pressure so sound waves are a type of pressure wave

26
Q

How do sound waves in ears transfer sound?

A

The sound wave travels down the auditory canal towards the ear drum
The pressure of the sound wave exerts a force on the eardrum which causes the ear drum to vibrate
The ear drums vibrations are transferred onto 3 small bones which then transfers vibrations into the inner ear
The inner ear nerve cells detect the sound and transfer electrical signals to the brain

27
Q

What frequency do humans hear at?

A

20Hz - 20,000Hz

28
Q

What is ultrasound?

A

Sound waves with a frequency of greater than 20,000Hz

29
Q

What is infrasound?

A

Sound waves with a frequency less than 20Hz

30
Q

What may happen to ultrasound when meeting a boundary between two media?

A

May be partially reflected, transmitted or absorbed

31
Q

When is the greatest percentage of the wave reflected between media?

A

When the difference in the speeds in the media is large

32
Q

What is echo sounding? What does it use? And what does it show?

A

Echo sounding is a sound wave which uses ultrasound to detect the depth of the ocean.
The time it takes for the wave to return determines the depth

33
Q

How is ultrasound used in medicine?

A

To construct images of a foetus
To generate images of internal organs
As a medical treatment to remove kidney stones

34
Q

What is an ultrasound detector made of

A

A tranduscer which detects and producers a beam of ultrasound

35
Q

How does an ultrasound work

A

The ultrasound waves are reflected back to the tranduscer by boundries between tissues in the path of the beam
When these echoes hit the tranduscers they generate electrical signals that are sent to the ultrasound scanner to build an image

36
Q

Is ultrasound harmful?

A

No it is believed to be harmless and non-invasive

37
Q

How are ultrasounds used in industry?

A

A crack in a metal will cause some kind of bump on the oscilliscope as the wave is reflected back earlier than the rest

38
Q

What waves do earthquakes produce?

A

P-Waves (primary waves)

S-Waves (secondary waves)

39
Q

How are earthquake waves detected?

A

Using a seisometer

40
Q

P wave properties

A 
Longitudinal waves
Can pass through solids and liquids
Faster than s waves
They are low infrasound waves 
Only refract when pass through different layers of the earth
41
Q

S wave properties

A

Transverse waves
Cant move through liquids only solids
Slower than P waves

42
Q

What do seismic waves show?

A

Only P waves are detected on opposite sides of the earth so the mantle is solid as both waves can pass through it but the outercore is liquid
The inner core is solid due to the size and positions of the shadow zones created by p waves.

Physics paper 2 AQA (4 decks)

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