Waves Flashcards
What is a wave caused by?
Oscillations of particles or FIELDS
What is a progressive wave?
Transfers energy from one place to another without transferring matter
What are the features of waves? [5]
-Amplitude (A), metres
-Wavelength (λ), metres
-Frequency (f), hertz
-Time Period (T), seconds
-Wavespeed (c), m/s
What are radians and what is its symbol?
Its another measurement for angles
Its symbol is pi
1 radian = 180 degrees
What is phase difference?
How far one wave lags behind the other
What is path difference?
The distance, measured in metres between two points which are out of phase
What happens if two points are one wavelength apart?
Then there is no phase difference between them
[this is because they are in phase]
What is an unpolarised wave?
Waves that oscillate in multiple directions/planes
What is polarisation?
The process of restricting an unpolarised wave into one plane
[this is done by using a polarising filter aka polaroid]
What is superposition?
When two waves combine /overlap to form a single wave aka resultant wave
What happens when 2 waves travelling in opposite directions superpose?
It forms a standing waves which doesn’t transfer energy ; instead it uses its energy to oscillate
[they need to be travelling opposite directions to superpose]
What is coherence?
When waves have similar wavelength, frequency and a fixed phase difference
[standing waves have to come from coherence]
Why are they called standing waves?
Because they’re restricted to one medium
What is interference?
An overall pattern that results when two or more waves interfere with each other
What is destructive interference?
When two waves are out of phase and their individual displacements cancel each other out producing zero resultant displacement OR it can reduce it
