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waves Flashcards

1
Q

waves do what

A

Waves transfer energy from one place to another without transferring matter.

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2
Q

amplitude

A

the maximum displacement from the equilibrium position (the x-axis).

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3
Q

wavelength

A

the distance of one entire oscillation of that wave.

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4
Q

time period

A

the time it takes for one entire oscillation of a wave.

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5
Q

frequency

A

The total number of wave cycles completed in one second

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6
Q

The formula for frequency is:

A

frequency=1/time

(time when one complete oscillation)​


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7
Q

The formula for wave speed is:

A

wave speed (metre/second, m/s) =
frequency (hertz, Hz) × wavelength (metre, m)

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8
Q

parallel to the direction of energy transfer is a:

A

Longitudinal

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9
Q

perpendicular to the direction of energy transfer is a

A

Transverse wave

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10
Q

examples of transverse wave

A

light
radio
ripples
waves on strings for guitar

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11
Q

examples of longitudinal waves

A

sound
seismic p waves

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12
Q

Describe one piece of evidence that shows when a sound wave travels through the air it is the wave and not the air itself that travels

A

A vibrating drum skin does not move the air away to create a vacuum (around the drum).

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13
Q

period

A

length of time it takes one wave to pass a given point

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14
Q

velocity

A

speed of the wave in the direction that its travelling

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15
Q

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

A

sound- stand infront of large wall measure the time it takes for an echo of loud sound to reach you

velocity-measure the time it takes for a wave to travel between two fixed points such as buoys

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16
Q

Calculate depth or distance from time and wave velocity

A

distance=speedx time

is there is an echo divide by 2

17
Q

reflection

A

when a wave bounces off a boundry

18
Q

refraction

A

when a wave passes into an new material but changes speed and direction when travelling

19
Q

transmission

A

when a wave passes through a material and is not absorbed or reflected

20
Q

absorbtion

A

when a wave dissapears as the energy it is carrying is transferred into a new material

21
Q

Explain how waves will be refracted at a boundary in terms of
the change of direction and speed

A

When wave crosses boundary between materials at angle changes direction which means refracted

  1. Waves crosses a high density material a slower wave
    wave crossing low density material will have a higher speed

3 how much wave speeds up or slows down will affect refracted.

wave crosses boundry and slows down bends towards normal
sppeds up bend away from normal

  1. The wavelength of wave changes when refracted, but frequency stays the same
  2. If the wave is travelling along the normal it will change speed, but it’s not refracted

27 / 29

22
Q

Recall that different substance may absorb, transmit, refract or reflect EM waves in ways that vary with WL

A

different WL will A,T,R differently
just like how light waves through glass will be A,TR etc

23
Q

Describe the processes which convert wave disturbances between sound waves and vibrations in solids

A

Sound example longitudinal wave -
compressions (regions of higher density)
rarefactions (lower density).
These cause changes in pressure,
vary in time with the wave.
waves hit the solid, the variations in pressure cause the surface of the solid to vibrate in sync with the sound wave.

24
Q

Explain why such processes only work over a limited frequency range, and the revelance of this to human hearing

A

NOT ABOUT THE VOLUME (like tv volume)
as humans range of frequencies that we can hear. animals have different.
Hair cells become damaged which cant receive the vibrations

25
Q

Recall that sound with frequencies greater than
20 000 hertz, Hz, is known as

A

ultra sound

26
Q

Recall that sound with frequencies less than 20 hertz,
Hz, is known as

A

infrasound

27
Q

explain uses of ulta sound

A

Sonar
uses ultrasound detect objects underwater
The sound wave is reflected off the ocean bottom
The time sound wave return used to calculate the depth of the water
The distance the wave travels is twice the depth of the ocean
This is the distance to the ocean floor x2

Foetal Scanning
ultrasound used images of a foetus in the wombmade up of a transducer that produces and detects a beam of ultrasound waves into the body
waves are reflected back to the transducer by different boundaries between tissues in the path of the beam
For example, the boundary between fluid and soft tissue or tissue and bone

exploration of earths core
p waves - move faster than s waves
longitudinal but cant pass gas
low frequency sound waves known as infrasound

s waves
S-waves are slower than P-wave
unable to travel through liquid
only travel through solids

28
Q

explain uses of ulta sound

A

Sonar
uses ultrasound detect objects underwater
The sound wave is reflected off the ocean bottom
The time sound wave return used to calculate the depth of the water
The distance the wave travels is twice the depth of the ocean
This is the distance to the ocean floor x2

Foetal Scanning
ultrasound used images of a foetus in the wombmade up of a transducer that produces and detects a beam of ultrasound waves into the body
waves are reflected back to the transducer by different boundaries between tissues in the path of the beam
For example, the boundary between fluid and soft tissue or tissue and bone

exploration of earths core
p waves - move faster than s waves
longitudinal but cant pass gas
low frequency sound waves known as infrasound

s waves
S-waves are slower than P-wave
unable to travel through liquid
only travel through solids

29
Q

what does the discovery of p and swaves show

A

The mantle is solid – this is because both types of wave can pass through it
The outer core of the Earth is liquid – hence no S-waves can penetrate it
The inner core is solid – this is due to the size and positions of these shadow zones which indicate large refraction taking place

30
Q

Describe how changes, if any, in velocity, frequency and
wavelength, in the transmission of sound waves from one
medium to another are inter-related

A

Velocity of sound is directly proportional to the wavelength. Thus, if the velocity of sound doubles when it travels from one medium to another, its wavelength also doubles. The frequency of sound depends upon the source of sound, not the medium of propagation. Hence, it does not change.

31
Q

suitability of equipment to
measure the speed, frequency and wavelength of a wave in a
solid

A

suspend metal rod horizontally using clamp stand and rubber band
hit one end with hammer
get frequency app and note peak frequency
measure length of rod
wavelength=length x 2
use frequency and wavelength to calculate speed

32
Q

suitability of equipment to
measure the speed, frequency and wavelength of a wave in a liquid

A

set up ripple tank with straight dipper near one side of tank
fasten ruler to one of sides so u see markings
vary the current until see waves with wavelength half as long as tank
count waves form in 10 seconds
use the ruler to estimate the wavelength of waves
use wavelength and frequncy to work out speed
mark 2 points on same edege as ruler use stop watch to mesaure the time for it to go from one mark to the other

33
Q

ear path

A

sound waves move along ear canal and hit our eardrum causes vibrate which will transmit through osicles through the semi circular canals and into cochlea which converts into signals

34
Q

what happens when ultra sound hits medium

A

partial reflection

35
Q

Ppl trying to measure spped of sound in air

How could they imrpve the method

A

Make the distance longer
Cause 50m too short to produce measureable time
Give more accurate result

36
Q

Describe how hitting the rod causes sound wave to travel along the inside of the rod

A

Particles at end vunrate in fixed positions which cause neighbouring particles to vibrate

37
Q

Describe how dolphin use sound waves to see which object closest

A

Emit and recieve sound reflected from object
Differency in time to recieve echo
Sound recieved in shorter time is closest

38
Q

Explain how p and s waves show about density and nature of earths core

A

Where p and s waves detect
P waves arrive before s
Solid cause s waves only travel in solid
Mantle must be solid
Waves refract so mantle gets more dense as u go deeper

No waves
Must be liquid cause no waves go thru liquid
Core must be liquid
R refracted at the boundry

Only p waves
Arrive at different times cause travelled at different speeds
Very centre is solid cause travel faster than those that went tru liquid

gh (11 decks)

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