Waves Flashcards
What do waves transfer?
Energy without transferring matter
What are the 2 types of waves?
Transfers and longitudinal
What are transverse waves?
Oscillations are perpendicular to the direction of travel and energy transfer
Examples of transverse waves
Radio, microwave, light
What are longitudinal waves?
Oscillations are parallel to the direction ration of travel and energy transfer
What do longitudinal waves have that transverse waves don’t?
Compressions and rare fractions
Examples of longitudinal waves
Sound, p-waves
What is wavelength?
Length of 1 complete wave
What is amplitude?
Maximum displacement between from equilibrium
What is frequency?
Number of complete waves per second
What is a period?
Time taken for a whole wave to completely pass a single point
What is a wavefront?
The plane in which the wave travels (ie. The direction of the wave)
Velocity Equation:
Velocity = frequency x wavelength
What is frequency measured in?
Hertz
What is wavelength measured in?
Metres
Wave speed equation:
Wave speed= frequency x wavelength
What happens if you increase frequency?
Velocity increased
What happens if you increase wavelength?
Velocity increases
What is the relationship between period and frequency?
Period is inversely proportional to frequency
What happens if it’s a smaller period?
Higher frequency and greater velocity
What is the speed of sound in air?
330m/s
How can we use echo to measure sound?
Allows us to measure sound over a greater distance
What do you need to take into account when using echo to measure sound?
Double the distance as echo is there and back
Or half the time as echo takes time to go there and back
What can we use to investigate wave speed?
Ripple tank
When light meets a boundary, what 3 things can happen?
- Reflection
- Transmission
- Absorption
What does it mean when a light wave is reflected?
The waves bounce off the material
What does it mean when a light wave is transmitted?
The waves passes through the material
What does it mean when a light wave is absorbed?
Energy is transferred to the material
What is the Law Of Reflection?
Angle of incidence = the angle of reflection
What does the Law Of Reflection mean?
That wave speed, wave length and frequency DON’T change
Reflection practical: How can we improve the experiment and why do we need to?
Human error when drawing the dots and crosses (which indicate the light ray) as the line is quick thick. This makes it hard to judge the centre of the ray.
To improve, use a laser light or smaller slit to make the ray thinner and easier to draw.
What is refraction?
When waves change speed at the interface between materials
When light goes from air to glass its direction…
This is because…
As a result, it’s speed….. bending the wave ……… the normal.
Moves towards the normal
As it moves from a less dense to a more dense material
Decreases
Towards
When light goes from glass to air its direction…
This is because…
As a result, it’s speed….. bending the wave ……… the normal.
Moves away from the normal
As it moves from a more dense to a less dense material
Increases
Away from
When light enters the air or glass along the normal, what happens?
Nothing changes
What is infrasound?
Any sound wave less than 20 Hz
What are the 2 types of seismic waves?
Primary and secondary waves
What type of wave is a p wave?
Longitudinal
How fast is a p wave?
Fast
What medium do p waves travel through?
Liquid
Solid
What effect do p waves have on buildings?
Vibrate up and down
What type of wave is an S wave?
Transverse
What is the speed of S wave?
Slow
What medium do S waves travel through?
Solids
What effect does s waves have on buildings?
Vibrate back and forth
What is the S wave shadow?
No S waves reached
Becaus can’t transmit through liquid as they are transverse suggesting the outer core contains lucid
What is the p wave shadow?
Doesn’t get any p waves
2 wave shadows prove ty middle solid core as p waves can travel through solid and liquid but because of different mediums and therefore speeds they refract creating the shadows
What is frequency?
Number of complete waves per second
What is amplitude?
Maximum displacement from equilibrium
What is a wavelength?
Length of 1 complete waves per
What frequency in
Hertz
What’s amplitude measured in?
Metres
What is range of human hearing?
The range of human hearing is 20 - 20 000 Hz
What is ultrasound?
Any sound above 20 000 Hz
Benefits of ultrasound:
Locate water hazards
Prenatal scanning
Less invasive
Safer as no radiation
Cons of ultrasound:
Can produce pressure oscillations in tissue
Doesn’t tafvel well through bones in head or lungs
What’s sonar?
Sound navigation and ranging
A sign,a is sent out and time taken for source and back again as its reflects (echo location)
Uses of ultrasound:
Depth evaluation
Sonar
Prenatal scanning l
Animals eg. Dolphins and dogs
Ultrasound imaging
F=
1 over time period
What is a time period
Time for complete wave
What is refraction?
Refraction is the change in speed of a wave as it reaches a boundary between two media, usually resulting in a change in direction (if it enters at an angle).
What is refraction?
Refraction is the change in speed of a wave as it reaches a boundary between two media, usually resulting in a change in direction (if it enters at an angle).
How does sound travel from the ear drum to the cochlea?
Vibrations of air particles are transmitted down the ear canal to the ear drum.
The ear drum vibrates with the same frequency as the air particles hitting it.
The ear drum is connected to the three bones: the hammer, anvil and stirrup. These pick up and amplify the vibrations. The stirrup vibrates the cochlea. (… inside which the vibrating fluid causes a membrane with tiny hairs on to vibrate, converting the mechanical vibrations into electrical signals which are passed down the auditory nerve to the brain.)
How does the human ear work?
- The outer ear collects the sound which travels into the ear
- The sound waves cause the eardrum to vibrate at the same frequency
- This is amplified by three ossicles (small bones)
- This causes the hair in the cochlea to vibrate
- The cochlea converts the vibrations into electrical signals
- The signals are passed to brain through the auditory nerve
- The brain converts the electrical signals into sound
