Topic 4 Flashcards

Done except for few specpoints

1
Q

4.1
What is a wave

A

Method of transferring:
-E & info
-From a source
-w/o matter

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2
Q

4.2
Define the term compression

A

Areas in the wave where the particles are close together

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3
Q

4.2
Define the term rarefraction

A

Areas in the wave where the particles are far apart

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4
Q

4.2
Describe evidence that with water and sound waves it is the wave and not the water or air itself that travels

A

-Water/air molecules oscillate in place as E passes through
-Molecules themselves don’t travel w/ wave

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5
Q

4.3
Define the term frequency. What is it measured in?

A

-No. of waves passing a given point/s
-Hz (Hertz)

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6
Q

4.3
What is the equation for working out the frequency of a wave?

A

f=1/T

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7
Q

4.3
Define the term wavelength
What is it measured in?

A

-Distance from peak to peak or trough to trough
-m (metres)

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8
Q

4.4
Define the term amplitude
What is it measured in?

A

-Distance from rest position to peak or trough
-m (metres)

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9
Q

4.4
Define the term period
What is it measured in?

A

-t for 1 wave to pass given point
-s (seconds)

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10
Q

4.4
What is the equation for working out the time period of a wave?

A

T=1/f

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11
Q

4.4
Define the term wave speed. What is it measured in?

A

Total distance covered by wave in given time period
(m/s)

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12
Q

4.5
Compare transverse and longitudinal waves

A

Transverse - Oscillation of particles PERPENDICULAR to direction of wave

WHEREAS

Longitudinal - Oscillation of particles PARALLEL to direction of wave

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13
Q

4.5
State 4 examples of transverse waves

A

-Sea/water waves
-Light waves
-Other electromagnetic waves
-Some seismic waves

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14
Q

4.5
State 2 examples of longitudinal waves

A

-Sound waves
-Some seismic waves

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15
Q

4.6
State 2 equations for wave speed (velocity)
State their units

A

Wave speed(m/s) = frequency(Hz) × wavelength(m)
v=f×λ

Wave speed(m/s) = distance(m) ÷ time(s)
v=x/t

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16
Q

4.7
Describe how to measure the velocity of sound in ripples on water surfaces

A

-Use ripple tank w/ vibrating bar
-Bar connected to power pack
-Vibrates -> waves on water surface
-Lamp above ripple tank
-White paper under w/ ruler alongside
-Light shines thru water -> image of waves on paper
-Record w/ phone
-Freeze image & measure λ
-Find f: record timer + waves & watch in slow motion
-Count no. of waves passing point in 1 sec
-v=f×λ

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17
Q

4.7
Describe how to measure the velocity of sound in ripples on water surfaces

A

-Select wave
-Measure tank length
-Measure t takes to move tank length
-s=d/t

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18
Q

4.8P
The sound wave released from a ship took 0.12 seconds to return. The speed of sound in water is 1500 m/s. What was the depth of the sea?

A

90m

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19
Q

Define the term oscillation

A

VIBRATION of particles back and forth around an EQUILIBRIUM point

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20
Q

What are the colours of visible light?

A

Red
Orange
Yellow
Green
Blue
Indigo
Violet

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21
Q

4.9P
Define the term absorbed

A

When a wave is taken in by a medium

22
Q

4.9P
Define the term transmitted

A

When a wave passes all the way through a medium

23
Q

4.9P
Define the term reflected

A

When a wave is cast back from a different medium

24
Q

4.9P
What is the normal?

A

Perpendicular line to the interface

25
Q

4.9P
What is the interface?

A

Boundary between two media e.g. glass & air

26
Q

4.9P
What is an incident ray?

A

Ray that approaches the interface

27
Q

4.9P
What is a refracted ray?

A

Ray that has been bent entering new medium

28
Q

4.9P
Define the term medium

A

Material through which waves are transmitted

29
Q

4.9P
Define the term refraction

A

The bending of waves when they change speed

30
Q

4.10PH
Which way will a wave bend/refract if it enters a denser medium? Describe the angle of refraction in relation to the angle of incidence

A

-Slows down so TOWARDS normal
-<r less than <i

31
Q

4.10PH
Which way will a wave bend/refract if it enters a rarer medium? Describe the angle of refraction in relation to the angle of incidence

A

-Speeds up so AWAY from the normal
-<r greater than <i

32
Q

4.10PH
An incident ray enters a medium and refracts. State 2 factors that will affect the angle of the refracted ray.

A

-The speed the ray travels in the two media
-The angle of the ray hitting the interface

33
Q

4.10PH
Describe what will happen when a light ray enters and leaves a glass block

A

-When incident ray hits interface slows down & bends TOWARDS normal
-When leaves glass bends AWAY from normal
-PARALLEL to original incident ray

34
Q

4.11
How do different substances absorb, reflect, refract and transmit waves?

A

In ways that vary w/ λ

35
Q

4.12PH
Explain why the human ear only works over a limited frequency range

A

-Ossicle size = too small
-Limited hair cell lengths

36
Q

4.12PH
Describe how the human ear works
[6 marks]

A

-Ear detects sound
-Pinna funnels sound waves into ear canal
-Sound waves travel along ear canal and cause ear drum to vibrate
-Ossicles (3 tiny bones) transmit vibrations to cochlea
-Cochlea generates an electrical signal
-Auditory nerve transmits electrical signal to brain

37
Q

4.13PH
What is ultrasound?

A

Sounds with frequencies greater than 20,000 Hz

38
Q

4.14PH
What is infrasound?

A

Sounds with frequencies less than 20 Hz

39
Q

4.15PH
Explain why ultrasound is used for foetal scanning instead of x-rays

A

X-rays EMIT radiation -> can harm baby

40
Q

4.15P
State 4 uses of ultrasound

A

-Jewellery cleaning
-Teeth cleaning
-Foetal scanning
-Sonar

41
Q

4.15P
State 2 uses of infrared sound

A

-Exploration of Earth’s core
-Communication by animals

42
Q

4.15P
Describe how sonar works

A

-Boat sends ultrasound into water
-Ultrasound reflects from sea bed
-Boat detects echo
-Measures time between sending and receiving wave
-x=v×t/2 to figure out depth

43
Q

Explain what states of matter sound waves would travel the fastest in

A

-Solids & liquids
-Particles closer together
-Less E dissipated

44
Q

Which colour travels the fastest? Describe its wavelength

A

Red (longest wavelength)

45
Q

Describe the relationship between wavelength and speed

A

-Directly proportional
-As waveLENGTH increases, speed increases

46
Q

Which waves travel fastest, P waves or S waves? Explain both

A

-P waves
-Push and pull motion between particles transfers energy forward very quickly
-In S waves, energy transferred forward slower because transverse

47
Q

What media can P waves travel through?

A

Solids & liquids

48
Q

What media can S waves travel through?

A

Solids

49
Q

What type of wave is a P wave?

A

Longitudinal

50
Q

What type of wave is an S wave?

A

Transverse wave

51
Q

Why are P waves and S waves constantly bending as they travel through the earth?

A

Rock density increases -> refract