Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

bmat physics > waves > Flashcards

waves Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

what are waves

A

waves transfer energy by causing particles of matter to oscillate (move in one direction then the opposite direction from one side to the other of a fixed point.- pendulum is an example of an object that oscillates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

longitudinal waves

A

oscillations are parallel to (in the same plane as the direction of energy transfer)
example of a longitudinal wave
a spring being compressed and returning to its original shape
compressed region- compression
stretched region- rarefaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

transverse waves

A

oscillations are perpendicular to the direction of energy transfer
amplitude- from peak to bottom
wavelength- from bottom of one wave to the next. from one trough to the next.
from bottom to top of peak- amplitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

example of longitudinal waves

A

sound waves, seismic waves (p seismic waves)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

examples of transverse waves

A

EM electromagnetic waves
microwaves, light and uv rays
transverse waves- oscillations are perpendicular to direction of energy transfer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

wavelength m

A

distance between point on one wave and point on another wave that is exactly identical
crest to crest or trough to trough
lambda represents wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

amplitude m

A

measured in metres as it is a distance
maximum distance a particle can be displaced from rest position to a crest or trough. crest is highest point of wave and trough is lowest point of wave.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

crest

A

highest point on a wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

trough

A

lowest point on a wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

frequency meaning

A

number of waves passing a point per second. 1HZ means 1 complete wavelength per second.
50HZ means 50 complete wavelengths per second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

for sound waves what does a higher amplitude mean

A

for sound waves a higher amplitude means a louder sound and a higher frequency means higher pitch.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

in sound waves what is amplitude directly proportional to

A

the volume for example. higher amplitude louder sound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

in sound waves what is the frequency directly proportional to

A

frequency is directly proportional to the pitch. higher frequency higher pitch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

oscillation

A

one complete wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

frequency equation

A

1/time period
time period time it takes for one complete wavelength (oscillation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

wavespeed equation two equations
state equation involving distance and time

A

distance travelled by the wave divided by time taken

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

second equation of wavespeed

A

frequency (hz) x wavelength m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

frequency and what are inversely proportional

A

frequency= wavespeed/ wavelength
so frequency and wavelength are inversely proportional

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

longitudinal waves such as sound waves and siesmic p waves travel faster through solids than liquids and slowest in gases why?

A

because waves transfer energy causing particles of matter to oscillate. an object with a higher density such as solids allow the wave to travel faster than an object with low particle density such as gas as there are more particles of matter to oscillate in solids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

sound waves cannot travel through what

A

sound waves cannot travel through a vacuum as they transfer energy to particles of matter causing them to oscillate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how come electromagnetic waves can pass through a vacuum

A

conversely, the particles in em waves are the electrons in the wave itself so it doesnt not require additional matter and can travel through a vacuum.

22
Q

how can the speed of an em wave change

A

if the medium through which it is travelling changes such as air glass water.

23
Q

speed and wavelength are directly proportional, frequency is usually constant so changes in speed of wave usually results in wavelength changes.

A

speeds and wavelength are directly proportional so changes in speed result in changes in wavelength

24
Q

list the seven types of EM WAVES

A

-gamma
-infrared
-uv rays
-x rays
-microwaves
-radiowaves
-visible light red blue

25
Q

radiowaves
-wavelength
-uses
-dangers

A

wavelength >10cm
More than 10cm more than 0.1m
uses- communication
dangers- null

26
Q

microwaves
wavelength
uses
dangers

A

wavelength= 0.1m 10^-2m
uses- wavelengths that pass through water
communication
wavelengths absorbed by water
cooking
dangers-must be kept inside microwaves by metal grille or could heat the body

27
Q

infrared
wavelength
uses
dangers

A

wavelength= 10^-5 m
uses- heat is radiated as infrared
-used for heat
-cameras
cooking grilling toasting remote controls
dangers- infrared repsonsible for burns and greenhouse effect

28
Q

visible light blue red
wavelength
uses
dangers

A

wavelength= 10^-7m
uses-optical fibres
-dangers- eye damage by looking directly at sun

29
Q

ultraviolet
wavelength
uses
dangers

A

wavelength= 10^-8m
uses- floursecent marking chemicals are used which absorb uv light and emit visible light
dangers- skin cancer and ionising radiation

30
Q

x ray
-wavelength
-uses
-dangers

A

wavelength- 10^-10m
uses- medical imaging
dangers- ionising radiation

31
Q

gamma
wavelength
uses
dangers

A

wavelength= 10^-12m
uses- radiotherapy
cancer
medical therapy
sterilisation
dangers- ionising radiation

32
Q

acronym of order of electromagnetic waves

A

RMIVUXG
radiowaves
microwaves
infrared
visible light blue and red
ultraviolet
x rays
gamma rays

33
Q

ultrasound meaning

A

consists of sound waves with a frequency higher than 20khz

34
Q

human hearing limit

A

20hz-20khz
corresponds to a range of sound speeds and wavelengths calculated by
wavespeed ms_1= wavelength m x frequency s-1

35
Q

what are the uses of ultrasound

A

-can be used for non invasive medical imaging such as feotal scanning
-in depth detection sonar

36
Q

how is ultrasound used in medical imaging

A

ultrasound can detect the boundary between different tissue types as certain fractions of ultrasound waves are reflected at each boundary
time taken for reflected waves to reach detectors corresponds to depth of each boundary (tissue type)
these metrics can be combined to produce medical imaging of soft tissue

37
Q

what is meant by the term ionising radiation
uv
xrays
gamma rays

A

have enough energy to remove an electron and create a charged particle. if this happens in cells, it causes dna mutation and increases risk of cancer.

38
Q

reflection meaning

A

a wave bounces off a surface without being absorbed by it, usually causes wave to change direction

39
Q

law of reflection

A

angle of incidence= angle of reflection

40
Q

refraction of light

A

light bends as it passes close to edge of an object

41
Q

refraction of waves

A

wave enters a medium with a different optic density e.g air to glass and changes direction due to change in speed. a wave entering a medium at 90 degrees will change its speed but not its direction

42
Q

angle of incidence

A

angle between normal and incidence ray

43
Q

angle of refraction

A

angle between normal and refraction ray

44
Q

what is a spectrum

A

when a ray of white light enters a prism it splits into a rainbow from red to violet. light at the red end of the spectrum is refracted least and light at the blue end of the spectrum is refracted the most this is because red has a longer wavelength than blue. blue bends red resists blue more refraction as shorter wavelength.
shorter wavelength more refraction

45
Q

sound waves reflect and refract. what happens to speed of sound waves asthey enter a more dense medium

A

they speed up and refraction occurs

46
Q

doppler effect

A

when source moves close to observer, wavelength decreases and frequency increases
when source moves away from observer, frequency decreases and wavelength increases
the faster the movement the greater the doppler shift/

47
Q

how are sound waves produced

A

by a vibrating source.
the vibrating source causes the surrounding medium to vibrate and this pattern of vibrations travels away from the source as sound waves.

48
Q

the sound waves have the same frequency pitch as the vibrations of the source
the amplitude (loudness of the sound) waves depends on amplitude of vibrations of the source
the speed of soundwaves is determined by the medium of which they travel through and not the source

A

when sound arrives at a detector (eg micorphone or human ear) the sequence of compressions and rarefractions causes the pressure of the detector to vary. this exerts a varying force on the detector and this is what is detected (the eardrum is moved by this force)
soundwaves obey the law of reflection where the angle of incidence= the angle of reflection

49
Q

what is an echo

A

the sound heard when soundwaves reflect off one or more surfaces.

50
Q

reflection of sound or ultrasound waves can be used to measure distances with equation

A

distance= velocity ms_1 x time (seconds) /2
time taken for wave to travel from emitter to object and back again

bmat physics (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions