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

wave definition

A

disturbances that transmit energy from one place to another without transferring matter

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

propagation direction definition

A

direction of travel of a wave

direction energy is transported

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

longitudinal wave definition

A

disturbance cause by wave is felt in propagation direction

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

transverse wave definition

A

disturbance caused by wave felt perpendicular to propagation direction

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

amplitude definition

A

A

maximum displacement of a wave from resting point

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

frequency definition

A

f
number of waves passing a point per second
measured in Hz

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

wavelength definition

A

lambda
length of full cycle of a wave
distance between the same points on 2 waves

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

shape of transverse waves

A

peaks and troughs above and below equilibrium

oscillated perpendicular to propagation direction

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

examples of transverse waves

A

EM waves
waves on guitar string
S-waves

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

shape of longitudinal waves

A

vibrates in propagation direction

areas of high density (compression) as oscillating particles forced close together, areas of low density (rarefraction)

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

examples of longitudinal waves

A

sound waves

P-waves

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

S-waves vs P-waves

A

both mechanical waves
S-waves travel transverse through solid rock only, slower
P-waves travel longitudinal through solid + liquid rock, faster

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

wave equation

A 
wave speed(m/s) = frequency(Hz) x wave length(metres)
v = f  x lambda
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

period definition and formula

A

T
how long it takes to complete 1 oscillation
T = 1/f

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

reflection definition

A

change in direction of a wave without change of speed, wavelength or frequency

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

law of reflection

A

angle of reflection = angle of incidence

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

refraction definition

A

change in direction of a wave as it travels from one medium to another with a different refractive index
greater difference in refractive index = greater change in speed and direction

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

how refraction occurs

A

waves meet new medium at angle to boundary (not perpendicular to boundary or else no change in direction, just less wave speed and wavelength)
enters medium w/ greater refractive index = bends toward normal
enters medium w/ lower refractive index = bends away from normal

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

how dispersion occurs and why

A

white light shone through a prism at an angle to the boundary
different wave lengths refracted by different amounts
splits into difference colours

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

sound type of wave

A

longitudinal

mechanical

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

sound features

A

requires medium to travel through
travels fastest through denser (solid) mediums
causes air molecules to vibrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

pitch

A

depends on frequency of sound waves
high-freq sound wave = high pitch, short wavelength
low-freq sound wave = low pitch, long wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

range of ultrasound

A

> 20kHz

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

range of infrasound

A

< 20Hz

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

volume

A

depends on amplitude of sound waves

26
Q

why pitch and volume are independent

A

frequency and amplitude are independent

27
Q

echo definition

A

delayed reflections one hears after an initial sound has passed

28
Q

how echoes occur

A

noise made
some of sound waves travels first to the ear and registered by brain
some of sound waves travels away from source, reflected off surface and heard by ear and registered by brain with time delay

29
Q

why sound waves change in direction due to refraction hard to hear

A

sound waves spread out too much

30
Q

electromagnetic waves summary

A

all transverse waves
spectrum divided into 7 regions based on wavelength/frequency
all have same speed

31
Q

speed of light in vacuum

A

3x10ms^-1

32
Q

radio waves defined as

A

longest wavelength of EM spectrum

wavelength > 10cm

33
Q

radio waves main uses

A

broadcasting
communication
e.g. radio/TV/mobile phone signals

34
Q

shortwave radio signals length + uses

A

wavelength: 10-100m
long distance communication (TV, FM)
signal bounces off ionosphere due to short wavelength

35
Q

longwave radio length and uses

A

wavelength: 1-10km

travel long distances because can diffract around Earth’s curved surface

36
Q

diffraction definition

A

involved change in direction of waves as they pass through an opening or around a barrier in their path
results in direction of wave changing + wave spreading out perpendicular to propagation direction + transmitting over greater area

37
Q

order of EM waves (wavelength longest to shortest)

A 
radio waves
microwaves
infrared radiolarian 
visible light
ultraviolet light
x-rays
gamma rays
38
Q

energy, wavelength and frequency

A

shorter wavelength = faster frequency (due to wave equation)

faster frequency = more energy

39
Q

microwaves in TV

A

transmitters produce microwaves able to pass through Earth’s atmosphere to satellites in space
bounces signal down to desired locations, picked up by satellite dish

40
Q

microwaves in mobile phone signals

A

signal from phone travels to nearest transmitter as microwaves then to other phones

41
Q

microwaves in cooking food

A

penetrates few centimetres into food before being absorbed by water molecules
water molecules vibrate (heats up), cooks food by conduction and convection

42
Q

microwaves dangers

A

frequency when used in communication too low to damage tissues
can cause internal hearing of body tissues with higher frequencies, causes burns

43
Q

how microwave ovens are safe

A

metal cases

screens over glass doors reflects and absorbs microwaves to prevent them from escaping

44
Q

infrared radiation features

A

wavelength: 700nm to 1mm

45
Q

infrared wavelength

A

700nm to 1mm

46
Q

how IR cameras work

A

good for producing images in the absence of visible light
detect IR to produce an image
more IR emitter = warmer region

47
Q

uses of IR

A 
monitoring temperatures 
heating food
security cameras
night-vision
automatic doors
short distance communication (remote controls)
optical fibres
48
Q

how optical fibres work

A

thin rods of high quality glass transmit information as infrared signals
repeatedly and rapidly reflects infrared from one end to the other

49
Q

greenhouse effect

A

Sun’s rays enters Earth’ atmosphere
some pass through outer atmosphere, some reflected back out into space
rays reach surface, some partially reflected or partially absorbed depending on object they incident on
surface of Earth radiates IR back into space
greenhouse gases in atmosphere absorb some of IR instead of reflecting it back to space
gases conduct, convect, radiate heat to surroundings

50
Q

greenhouse gases examples

A

carbon dioxide
water vapour
methane

51
Q

visible light wavelength

A

300nm to 700nm

52
Q

how sight works

A

visible light reflected off object into eye
lens refracts visible light focused onto retina
retina sends messages to brain via optic nerve to be interpreted

53
Q

what happens if intensity of incident light too high

A

if intensity of incidence light too high, causes blindness

54
Q

UV light wavelength

A

100nm to 400nm

55
Q

why we tan

A

skin absorbs UV light

turns darker to absorb more UV light to prevent it from reaching deeper tissue

56
Q

UV light uses

A

detect forged bank notes (real ones have fluorescent ink)
security pens
treatment of skin conditions, sterilise medical equipment
fluorescent lamps

57
Q

dangers of overexposure to UV light

A

eye problems

damage DNA, causes cancer

58
Q

X-rays wavelength

A

0.01nm to 10nm

59
Q

X-rays uses

A 
investigate internal structure of objects 
passes through less dense objects, absorbed by denser objects 
detect bone fractures
airport security (scan luggage)
60
Q

gamma rays wavelength

A

smallest wavelength

highest energy

61
Q

gamma rays uses

A

sterilise food+medical equipment

diagnosis + treatment of cancer

62
Q

X-rays/gamma rays dangers

A

high ionising ability
can damage greater number of cells
can cause tissue damage and cancer

BMAT Physics (7 decks)

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