WAVES Flashcards
(85 cards)
1
Q
distance (in terms of waves)
A
how far the wave has travelled from its starting point
2
Q
displacement (in terms of waves)
A
how far from the equilibrium point the wave has oscillated (how far up or down)
3
Q
what unit should wavelength be in
A
metres
4
Q
transverse waves
A
oscillations are perpendicular to the direction of energy transfer
e.g. light waves, seismic s waves
5
Q
longitudinal waves
A
oscillations that are parallel to the direction of energy transfer
e.g. sound waves, seismic p waves
6
Q
wavelength
A
distance of one entire oscillation of that wave
(from equivalent point on another wave from 1 wave)
7
Q
amplitude
A
the max. displacement from the equilibrium position (x-axis)
8
Q
time period
A
the time it takes for one entire oscillation of a wave
9
Q
unit for frequency
A
Hz
10
Q
3 things that can happen when a wave hits a surface
A
- absorbed 2. transmitted 3. reflected
11
Q
angle of incidence =
A
angle of reflection
12
Q
specular reflection
A
clear image
normals are in the same direction
boundary is flat
e.g mirrors
13
Q
diffuse/scattered reflection
A
cannot see reflection
light reflected at different directions
boundary is bumpy
normals all different
14
Q
oscillations are perpendicular in what waves
A
transverse
15
Q
oscillations are parallel to direction of energy transfer in what waves
A
longitudinal
16
Q
all _____________ waves require a medium to travel in
A
longitudinal
17
Q
period
A
time in secs for one wave to pass a point
18
Q
1 Hz =
A
1 wave per second
19
Q
wave speed
A
the speed that the wave moves through the medium
(the speed at which energy is transferred)
20
Q
what is a ripple tank used for
A
to observe the features of water waves
21
Q
equipment used in the ripple tank required prac.
A
lamp
vibrating bar
power pack
water
ripple tank
22
Q
method for ripple tank (required prac)
A
- set up - fill w water, connect motor, lamp
- wavelength - measure distance between crests
- frequency - count no. of crests passing a point in 10 secs - divide by 10 for freq.
4.wave speed - use formula
23
Q
how to measure wavelength of waves in liquid (required prac )
A
place ruler on paper
measure distance between 1 wave then 10 waves further (ten wavelengths)
divide by 10 to find 1 waveength
24
Q
how to find frequency of waves in liquid (required prac)
A
place timer next to paper
count no of waves passing a point in 10 secs
divide by 10 to get frequency for 1
25
how to determine wave speed in liquid (required prac.)
select wave
measure time it takes to move the length of the tank
divide distance travelled by time taken
26
equipment for waves in solids (req. prac)
Signal generator
, vibration transducer,
string/wire,
pulley,
masses,
ruler
27
method for waves in solids prac.
1. set up - Attach one end of a string to a vibration transducer connected to a signal generator. Pass the string over a pulley with masses to keep it taut.
2. create waves - adjust signal generator until string forms clear loops (standing wave)
3. wavelength - measure length of multiple loops and divide by no. of loops for wavelength
4. frequency - read frequency from signal generator
5.wave speed - use formula
28
what can the surface of a material do to a wave
transmit absorb or relfect
29
method for refraction and reflection req. prac.
1. Set Up: Use a ray box, slit, and lens to create a narrow ray of light.
2. Prepare Paper: Place a ruler on A3 paper and draw:
A straight line parallel to the ruler.
A normal (perpendicular line) at the center.
3. Trace the Block: Place a rectangular acrylic block along the first line and draw around it.
4.Shine Ray: Direct a ray of light at the normal on the block.
Observe the incident, reflected, and refracted rays.
5. Mark Paths: Mark the paths of:
The incident ray (one cross).
The reflected ray (one cross).
The refracted ray (two crosses).
6. Draw Rays: Remove the block and join the crosses with lines.
7. Repeat: Repeat the process with a rectangular glass block.
8. Measure Angles: Measure and record the angles of incidence, refraction, and reflection for both blocks.
30
variables in the reflection and refraction req prac
Independent: Angle of incidence
Dependent: Angle of refraction
Control: Same block material, ray brightness, and setup.
31
what do you find about the angle of incidence and reflection in different materials (RQP)
is the same (they do not depend on the material)
32
will the angle of refraction be different in different materials (RQP)
yes
33
what type of wave is sound
longitudinal
34
normal human hearing range
20 Hz to 20,000Hz
35
do sound waves travel faster in solids or gases
solids (particles = close together = vibrations pass easier)
36
small amplitude =
quiet sound
37
large amplitude =
loud sound
38
sound waves can only move through a ...
medium
(sound waves move by particles vibrating)
39
what is a reflected sound wave
an echo
(echo)
(echo)
(echo)
40
ultrasound definition
soundwaves with a frequency higher than the upper limit of human hearing
41
waves that earthquakes produce
seismic waves (p waves, s waves)
42
p wave properties
go through solids and liquids
longitudinal
faster than s waves
43
properties of s waves
transverse
only through solids
slower than p
44
why cant s waves reach the solid inner core
cant pass through the liquid inner core
45
how were scientists able to discover the internal structure of the earth
dectecting which types of waves were detected at different places around the earth
( only p waves pass fully through)
46
properties of EM waves
transverse (oscillate perpendicular)
travel at diff speeds in diff mediums
47
what differentiaties the diff EM waves
wavelength
frequency
(inversely related)
48
when is gamma rays emitted
radioactive decay
49
when are visible light, ultra violet and xrays emitted
when electrons drop down energy levels
50
when is infra red radiation emitted
when bonds holding molecules together vibrate
51
for EM wave, the higher the density of the material ....
the slower the wave will travel through it
52
if speed of a wave increses ....
the wavelength must too
53
what does white light contain
all the wavelengths of visible light
54
(infared req prac) method
1. fill leslies cube w hot water
2. point infrared dectector at each of 4 surfaces
3, record amount of infrared emitted
55
what surfaces does a leslies cube have
shiny metallic
white
shiny black
matt black
56
results of leslies cube req prac
matt black emits most infrared emission
shiny metallic = least
57
method for absorbance of infrared req prac
1. put two metal plates (one w shiny metallic surface, one with matt black surface) on either side of an infrared heater and add a drawing pin to each side with vaseline
2. measure how much time hey take to melt off (matt black will fall off first
58
are matt black surfaces better at absorbing infrared radiation than shiny metallic surfaces
YES
59
when EM waves are generated/absorbed, ...
changes take place in atoms/ the nuclei of atoms
60
way electromagnetic waves can be generated
change in the nucleus
61
electromagnetic waves can be emitted and absorbed over a wide _________ range
frequency
62
hazards of ultraviolet rays
burns , cancer , aging prematurely
63
hazards of xrays and gamma rays
mutation of genes (ionising) - cancer
64
when are radio waves produced
when electrons oscillate in an electrical circuit
65
uses of radio waves + why
transmit TV signals +
they can travel long distances before being absorbed + spread out between hills
66
uses of microwaves + why
heating food +
alot of foods contain water + water molecules absorb the energy of microwaves - enrgy causes temp to increase
communicate w satelites in space + can pass through the earths atmosphere without being reflected/refracted
67
uses of infrared + why
electrical heaters + cookers
energy of infrared is easily absorbed by surface of objects
infrared cameras - check buildings for heat losses
68
use of visible light + why
communication using fibre optics
(eg telephone + cable TV signals)
has a short wavelength - can carry alot of info
69
uss of ultraviolet + why
energy efficient lightbulbs + has a short wavelength so it carries more energy than visible light
> energy of ultraviolet absorbed by the internal surface of the bulb + converted to visible light
sun tanning beds - BUT increases risk of cancer + aging
70
uses of xrays and gamma rays + why
medical imaging + treatments (xray = broken bones, gamma = cancer)
pass easily through body tissue
71
What is a concave lens?
A concave lens is a diverging lens that spreads out light rays that pass through it.
72
What type of image does a concave lens always produce?
A concave lens always produces an image that is virtual, upright, and smaller than the object.
73
How do concave lenses affect parallel light rays?
Parallel light rays refracted by a concave lens diverge as if they came from a point called the principal focus on the same side as the object.
74
What is the focal length of a concave lens?
The focal length of a concave lens is the distance between the optical center and the principal focus, where diverging rays appear to come from.
75
What is a convex lens?
A convex lens is a converging lens that bends light rays towards a focal point.
76
Q: What types of images can a convex lens produce?
A convex lens can produce:
Real, inverted, and magnified/diminished images (when the object is beyond the focal point).
Virtual, upright, and magnified images (when the object is closer than the focal point).
77
How do convex lenses affect parallel light rays?
Parallel light rays passing through a convex lens converge at the principal focus on the opposite side of the lens.
78
: What is the focal length of a convex lens?
The focal length is the distance between the optical center and the principal focus, where parallel rays meet.
79
TRUE or FALSE - diffuse reflection does produce an image
FASLE! - material is rough + uneven
80
TRUE or FALSE - specular relfection produces an image
TRUE
81
what does the colour of an object depend on
which wavelengths of light are reflected and absorbed
82
if a green filter was put infront of visible light, what colour would you see and why
green because all the other colours are being absorbed but green in transmitted through the filter
83
why do white objects appear white
they reflect all of the wavelengths of light equally
84
TRUE or FALSE - all objects, no matter what temp, emit and absorb infrared radiation
TRUE ( hotter will emit more than cooler)
85
what does a perfect black body do
absorbs all of the radiation incident on
no radiation reflected or transmitted
