Topic 4- Waves Flashcards

1
Q

What do waves transfer?

A
  • Energy
  • Not matter
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2
Q

How do we know matter doesn’t move in sound and light waves?

A

Light- particles oscillate up and down
Sound- particles vibrate back and forth

  • Ducks (toy) don’t move in water
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3
Q

What is frequency?

A

How many waves per second

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4
Q

What is wavelength?

A

Length of a full wave, from peak to trough

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5
Q

What is amplitude?

A
  • The height, equilibrium to the peak/trough
  • Loudness of a sound wave/ brightness
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6
Q

What is the period?

A

How many seconds it takes one complete wave to pass a point.

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7
Q

What is the wave velocity?

A
  • Speed of the wave in a given
    direction
  • changes in different mediums
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8
Q

What is a wavefront?

A
  • Lines that show the peak of a wave that vibrate in unison.
  • Equal distance from eachother
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9
Q

What is a longitude wave?

A
  • A wave with areas of compression and rarefaction
  • Oscillations occur parallel to the energy movement
  • sound waves
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10
Q

What is a transverse wave?

A
  • Wave with a peak and trough
  • Oscillations occur perpendicular to the energy movement
  • Light/electromagnetic waves
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11
Q

What are two examples of longitudinal waves?

A
  • Sound
  • P seismic
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12
Q

What are three examples of transverse waves?

A
  • Electromagnetic (light)
  • S seismic
  • Water
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13
Q

What are properties of P seismic waves ?

A
  • Can travel through solids and liquid
  • Produced by earthquakes
  • Faster than S seismic
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14
Q

What are properties of S seismic waves ?

A
  • Slower than P seismic
  • Only travel through solids
  • More destructive
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15
Q

How do we calculate wave speed?

A

Wave speed= frequency x wavelength
v=fxλ

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16
Q

Describe how to measure the velocity of sound in air with humans + what are the issues?

A

1) Place two people across a measured distance (e.g 100m)
2) Person A makes a visual and noise making gesture (e.g loud clap)
3) Person B beings top watch when sees and ends when hears
4) Repeat
5) Human reaction times differ for sound + light

17
Q

Describe how to measure the velocity of sound in air in microphones?

A

1)Place 2 microphones 1 metre apart
2)attach to a computerised ossciloscope
3)Make a loud bang at microphone 1
4)M-1 and M-2 will pick up sounds at different times

18
Q

Describe how to measure the velocity of sound in ripples?

A

1) Time how long it takes one ripple to move between 2 fixed points

19
Q

Core Practical: Investigate suitibility of equipmenent to find the frequency, speed and wavelength of a wave in a fluid

A

1) Record a ripple tank (frequency =no. of waves per second)
2) Place ruler udner ripple tank + use shadows to find wavelength
3) Wave speed = wavelength x frequency

20
Q

Core Practical: Investigate suitibility of equipmenent to find the frequency, speed and wavelength of a wave in a solid

A

1) Suspend metal rod with a clamp stand and a rubber band
2) Use a data logger
3) Hit one end with a hammer
4) Input known distance/ time measured = speed

21
Q

How to calculate depth from time and speed of a wave?

A

(time/2)x speed

22
Q

What is transmission

A

-Wave passes through an object without being absorbed

23
Q

What is reflection?

A

-Wave bounces off the boundry between 2 different mediums
-Angle of incidence= Angle of reflection

24
Q

What is refraction?

A

1) An wave speeds up/ slows down when entering a materil with a different density
2) To keep the same frequency, its wavelength shorterns (all inter-related)

incidence ray, refracted ray and emergant ray

25
Q

Do sound waves speed up or slow down in denser mediums?

A

-speed up
-Longitudinal, closer particles

opposite for light

26
Q

If a wave slows down it bends which way when refracted?

A

Towards the normal line (90 degrees to object)

e.g light in denser, sound in less dense

27
Q

How do objects interact with different wavelengths?

A

-differently
-some absob/ transmit/ reflect
-e.g why we see colour

28
Q

Parts of the human ear?

A

1) Ear canal
2) Ear drum
3) Ossicles (3 small bones)
4) semicircular canals
5) Cochlea
6) Auditory nerve

29
Q

How do humans hear?

A

-Sound is filtered into + travels along ear canal
-Cuases ear drum to vibrate
-Osiccles and semicircular canals transmit to cochlea
-Cochlea converts into electrical signal
-Across auditory nerve to brain to be interprited

e.g higher frequency = higher pitch

30
Q

Avg hearing range of humans?

A

20 Hz—>20,000 Hz

decreases when older due to wear + tear

31
Q

What is ultrasound?

A

sound with greater frequency than 20,000 Hz

32
Q

What is Infrasound?

A

sound with lower frequency than 20 Hz

33
Q

What can we use ultrasound for?

A

-Foetal scanning
-Sonar
-Industry poroducts
-Medical e.g kindey stone breaking

34
Q

How does feotal scanny work?

A

-Use an emitter + reciever on stomach
-Reflected when reach boundry
-processed into 3D image

safer than x-ray as less energetic (lower frequency), non ionising

35
Q

How does ultrasound work for industry work?

A

-Air in any cracks
-Ulttrasound is reflected too ealy
-reflected from boundry of product to air

36
Q

How does ultrasound work for sonar work?

A
  • Ultrasound emitted then reflected back t boundry to other density objects
37
Q

How does ultrasound work for kidney stones work?

A

-vibrates into smaller peices

non ionising

38
Q

How is infrasound used for discorvering earth’s core?

A

-P seismic waves travel through** liquid + solid**
-S seimsic only though solid
-S seismic found on same half of Earth as earthquake, wherease P everywhere + increased refraction
-Suggests their is liquid outer core
-Region where no waves are detected due to gradual refractions through mantle + liquid outer core

39
Q

What measures seismic waves?

A

seismometer