Waves Flashcards
How can waves be described?
Waves can be described as
oscillations
, or
vibrations
, about a rest position
What is an oscillation?
Vibration
What do sound waves do to particles?
sound waves cause air particles to vibrate back and forth
What do ripples in the water do to particles?
ripples cause water particles to vibrate up and down
Does the direction of oscillations vary?why?
The direction of these oscillations is the difference between longitudinal or transverse waves.
Describe the oscillations in longitudinal waves…
In
longitudinal waves
, the vibrations are parallel to the direction of wave travel
What are longitudinal waves?
A wave that moves in the same direction as the direction in which the particles are vibrating.
Describe oscillations in transverse waves….
In
tranverse waves
, the vibrations are at right angles to the direction of wave travel.
What is a transverse wave?
A wave that moves in a direction at right angles to the way in which the particles are vibrating.
What do mechanical waves do to to oscillations?
They cause oscillations of particles in a solid, liquid or gas and must have a medium
to travel through. Once the wave has passed, the medium ends up back in its rest position.
What is a medium?
A material through which a wave can be transmitted (propagate).
Are mechanical waves transverse or longitudinal?
Mechanical waves can be longitudinal or transverse.
Describe the oscillations in electromagnetic waves…..
Electromagnetic waves cause oscillations in electrical and magnetic fields. All electromagnetic waves are transverse
What do all waves transfer?
All waves transfer energy but they do not transfer
matter
.
What is matter?
Sub-atomic particles and anything made from them, such as atoms and molecules, are matter. Energy and forces are not matter.
What are the key parts of a wave?
Rest position
Displacement
Park
Trough
Amplitude
Wavelength
Time period
Frequency
What is the rest position of a wave?
the undisturbed position of particles or fields when they are not vibrating.
What is the displacement of a wave?
the distance that a certain point in the medium has moved from its rest position.
What is the peak of a wave?
the highest point above the rest position
What is the trough of a wave?
the lowest point below the rest position
What is the amplitude of a wave?
the maximum displacement of a point of a wave from its rest position.
What is the wavelength of a wave?
distance covered by a full cycle of the wave. Usually measured from peak to peak, or trough to trough
What is the time period of a wave?
the time taken for a full cycle of the wave. Usually measured from peak to peak, or trough to trough
What is the frequency of a wave?
the number of waves passing a point each second.
Describe the vibrations in a longitudinal wave….
In
longitudinal waves
, the vibrations are parallel to the direction of wave travel.
Name 3 examples of a longitudinal wave…
sound waves
ultrasound waves
seismic P-waves
What do longitudinal wave show areas of?
Longitudinal waves show areas of
compression
and
rarefaction
:
What is a compression?
An area of increased pressure. In longitudinal waves, the particles in areas of compression are closer together than on average.
What is rarefaction?
An area of reduced pressure. In longitudinal waves, the particles in areas of rarefaction are further apart than on average.
Describe the vibrations in transverse waves….
In
tranverse waves
, the vibrations are at right angles to the direction of wave travel.
What is a transverse wave?
A wave that moves in a direction at right angles to the way in which the particles are vibrating.
Name 5 examples of a transverse wave….
ripples on the surface of water
vibrations in a guitar string
a Mexican wave in a sports stadium
electromagnetic waves – eg light waves, microwaves, radio waves
seismic S-waves
How are transverse waves often demonstrated?
Transverse waves are often demonstrated by moving a rope rapidly up and down.
What is air made from?
Many tiny particles
What happens to the tiny particles in air when sound is created?
The air particles vibrate and collide with each other causing vibrations to pass between air particles
How these tiny particles help is hear sound?
They vibrate through a persons ear and vibrate their eardrum
What does light travel faster than?
Light travels much faster than sound and air
What types of waves are sound waves?
Longitudinal waves
What do longitudinal waves do to the tiny particles (sound)?
They cause the particles to vibrate parallel to the direction of wave travel
What can the vibrations caused by longitudinal waves do?
The
vibrations
can travel through solids, liquids or gases
What does the speed of sound depend on?
The medium through which it is travelling
What is the medium?
A material through which a wave can be transmitted (propagate).
What is the speed of sound when travelling through air?
About 330 metres per second (m/s)
What can sound not travel through?
A vacuum
What is a vacuum?
A volume that contains no matter
Why can sound not travel through a vacuum?
Because there are no particles to carry the vibrations
What may change when waves are transmitted at an interface (boundary)
It may change its direction
What is refraction?
Process by which a wave changes speed and sometimes direction upon entering a denser or less dense medium
What can all waves be?
Refracted
What is a ray diagram?
Diagram that represents the direction and angle of travel of light.
The density of a material is one of the factors that affects….. (refraction)
the speed that a wave will be transmitted through it.
What does the word “FAST” mean in terms of refraction?
F:aster
A:way
S:lower
T:owards
What are the 3 things that can happen to Waves arriving at the interface (boundary) between two materials?
They can either be
Reflected
Transmitted
Or absorbed
What happens to a wave when it is absorbed?
Energy is ‘taken-in’ by the material and the internal energy of the material will increase
What 3 factors will determine what happens to most of the wave energy?
The type of wave,
its properties such as wavelength, and the difference between the two media
What has a big effect on how much of the wave’s energy is reflected, absorbed or transmitted at an interface?
Wavelength
