Waves Flashcards
What must the frequency of a sound wave be greater than to make it an ultrasound
20,000 Hz
2 types of reflection
Specular
Diffuse
Which type of reflection requires a rough surface
Diffuse
Which type of reflection requires a smooth surface
Specular
What can happen to light when it meets a new medium
Reflection, refraction, transmission, absorbtion
What do waves transfer from one place to another
Energy
True or false, waves transfer matter from one place to another
False, they transfer energy
True or false, waves transfer energy from one place to another
True
Which out of energy or matter do waves transfer from one place to another
Energy
To travel from one place to another the waves vibrate/ what
Oscillate
Another word for oscillate
Vibrate
What do waves do when they travel from one place to another
Oscillate/ vibrate
Word for maximum displacement (distance between undisturbed ‘sea’ level and highest/ lowest point of wave
Amplitude
True or false, one entire oscillation is equivalent to the wavelength
True
What is meant by time period of wave
Time it takes for one complete wave to pass a fixed point
Difference between wavelength on displacement distance graph vs displacement time graph for wave
Displacement time- wavelength represents time period (how long it takes for 1 oscillation/ 1 wave to pass)
Displacement distance- wavelength still represents oscillation but with no reference to how long it takes
True or false, 1 complete oscillation = 1 full wave
True
What is meant by frequency of wave
Number of complete waves per second
Name for number of waves per second
Frequency
Frequency vs time period
Frequency= number of waves per second
Time period= time taken for one complete wave to pass a fixed point
What unit is wavelength measured in
Metres
What unit is wave speed measured in
M/s
2 main types of wave
Transverse
Longitudinal
In transverse waves the oscillations are what to the direction the wave is moving
Perpendicular
In longitudinal waves the oscillations are what to the direction the wave is travelling
Parallel
In what type of wave are the oscillations parallel to the direction the wave is travelling
Longitudinal
In what type of wave are the oscillations perpendicular to the direction the wave is travelling
Transverse
True or false, the direction of energy transfer is the same as the direction the wave is moving
True
Are all electromagnetic waves longitudinal or transverse
Transverse
True or false, all electromagnetic waves are longitudinal
False
They’re all transverse
What type of wave are sound waves
Longitudinal
2 examples of longitudinal waves
Sound waves
P- seismic waves
Name for type of diagram used to show reflection taking place
Ray diagram
In reflection the angle of incidence is always equal to what angle
The angle of reflection
In reflection what 2 angles are always equal
Angle of reflection
Angle of incidence
Name for dashed line drawn perpendicular to boundary in ray diagram
Normal
What is the normal
Dashed line drawn perpendicular to boundary in ray diagrams
Should the normal be a solid or dashed line
Dashed
In reflection if the angle of reflection is 45 degrees then what’s the angle of incidence
45 degrees
(As they’re always equal)
In reflection which angle are are we already given/ have to measure
Angle of incidence
(Check answer)
What is the ‘point of incidence’
Point in ray diagram for reflection where incoming ray (incident ray) meets the boundary
What type of reflection is a mirror and why
Specular reflection
Mirror is a smooth surface so all rays come in at same angle and therefore are reflected at the same angle (normals are all in same direction)
What type of reflection is paper
Diffuse
(As it has a rough surface, even though it doesn’t seem like it)
What type of reflection is paper
Diffuse
(As it has a rough surface, even though it doesn’t seem like it)
True or false, in both specular (smooth surface) and diffuse (bumpy surface) reflection the light rays are all coming in from the same direction
True
However in diffuse reflection the normals will all be pointing in different directions as they have to be perpendicular to the surface which isn’t the same everywhere, therefore the light will be reflected in lots of different directions
Why is light reflected in lots of different directions in diffuse reflection
The normals are all pointing in different directions due to the surface being bumpy and they have to be 90 degrees to the surface (so even though the waves all come from the same direction, they will have to be reflected off in different directions)
Which type of reflection produces a clear image
Specular
True or false, in both Specular and diffuse reflection the angle of incidence is always equal to the angle of reflection
True
Waves travel at different what in different materials
Speeds
Why do waves travel at different speeds through different mediums
Different materials have different densities
Do waves travel faster or slower in denser materials
Slower
In what type of material do waves travel fastest
Low density
(They travel slower in higher densities)
Another word for material
Medium
If a wave travels from a less dense medium to a more dense medium what happens to its speed
Slows down
(As waves travel slower in higher densities)
Which is more dense out of air and glass
Glass
(so waves will travel slower in glass than air)
If a wave travelling from air into glass hits the boundary at a perpendicular angle then what happens
It will keep travelling straight through but just change speed due to the different densities
(It will only be refracted if it comes in to the boundary at an angle)
In what scenario will the wave bend towards the normal
Going from less dense to more dense
When a wave enters a more dense medium does it bend towards or away from the normal
Towards
When a wave enters a less dense medium does it bend towards or away from the normal
Away
When does a wave bend towards compared to away from the normal
Going into more dense= bends towards normal
Going into less dense= bends away from normal
True or false, when waves enter a different medium their wavelength also changes
True
As wave speed = frequency x wavelength
And frequency always stays the same
Does the frequency of the wave ever change
No
Does the wavelength of the wave ever change
Yes
When the wave passes through a different medium and changes speed as frequency never changes and
Wave speed= frequency x wavelength
When the wave speed changes e.g passing through a different medium which other aspect of the wave also changes
Wavelength
(As wave speed = frequency x wavelength)
(Frequency never changes)
When electromagnetic waves are travelling through a …, they all travel at the same speed
Vacuum (or air)
What speed do all EM travel at through a vacuum/ air
3 x10^8 m/s
7 types of EM waves
Radio waves
Microwaves
Infra-red waves
Visible light
Ultraviolet rays
X rays
Gamma rays
Electromagnetic waves transfer energy from what to what
Source, absorber
2 things EM waves are grouped by
Wavelength, frequency