waves Flashcards
progressive wave is
example?
oscillation that travels through matter
all transfer energy, but not matter
sound
transverse waves? e.g.?
oscillations are perpendicular to the direction of energy transfer
em waves
longitudinal waves
example
oscillations are parallel to the direction of energy transfer
sound
amplitude definition
wavelength definition
maximum displacement from the equilibrium position
distance on a wave from peak to peak
frequency definition
the number of wavelengths passing a given point per unit time
when is a wave in phase/antiphase
in phase= particles oscillating perfectly in step with one another
antiphase= 180 degrees out of phase
reflection definition
law of reflection
when a wave changes direction at a boundary between two different media
angle of incidence = angle of reflection
refraction definition
where will it refract towards the normal?
when a wave changes direction as it changes speed (some reflection - partial reflection- will occur)
if it speeds up, it will refract towards the normal
what does refraction have an affect on
the wavelength but not its frequency
wave slows down - wavelength decreases
diffraction definition
diffraction occurs the most when?
when waves pass through a gap or travel round an object, they spread out
the size of the gap or obstacle is about the same as the wavelength of the wave
What is polarisation
The particles oscillate in one direction only- the wave is confined to a single plane
Which waves can be plane polarised
Transverse
Longitudinal cannot as oscillations already limited to one plane
What does partial polarised mean
When does this happen?
There are more waves oscillating in one particular plane but the wave is not completely plane polarised
When waves reflect off a surface
What is the intensity of a wave
UNITS
The radiant power passing through a surface per unit area
Wm-2
How to calculate intensity
Intensity and amplitude relationship
POWER / Cross sectional area
Intensity directly proportional to amplitude squared