Waves Flashcards
What is the frequency of a wave?
The number of complete oscillations per second in hz
What is the amplitude of a wave?
The displacement of the wave from a position of equilibrium in metres
What is the time period of a wave?
The time for one complete wave.
What is phase difference?
How far a particle/wave lags behind another particle/wave in degrees or radians.
What is phase?
The position of a certain point on a cycle of a wave.
What is wavelength?
The length of one complete wave, or one oscillation. Measured in metres.,
When are waves in phase?
If each wave has the same wavelength and frequency and if their phase difference is a multiple of 360
When are waves out of phase?
When they are an odd number of half cycles apart, where a half cycle is 180 degrees or pi rads.
Describe a transverse wave with two examples,
Waves which oscillate at a right angle to the direction of energy transferred.
Two examples are any EM wave such as light or radio waves. Another example is S waves from earth quakes
Describe longitudinal waves with two examples.
Waves which oscillations travel parallel to the direction of energy transferred.
Two examples are P waves and sound waves.
What is a polarised wave?
A wave that only oscillates in one plane.
Only one type of wave can be polarised, transverse or longitudinal?
Transverse as something can only be polarised if it is acting at 90 degrees to direction of energy transferred
What is an application of polarised filters?
Polarised sunglasses, they only allow light rays from the sun in one plane reducing the amount of light that reaches your eyes.
What is superstition?
Where the displacement of two waves whilst they pass each other are combined, the resultant displacement is the combined vector of the two waves.
What are the two types of superpostition?
Constructive interference and destructive interference.
What is constructive interference
Occurs when phase difference = n λ
When both waves have positive displacement in the same direction, they add to make a wave with a larger amplitude.
What is destructive interference and when does total destructive interference occur?
Occurs when path difference = (n+1) λ
Destructive interference is when the waves have displacement in opposite directions, making smaller amplitude. Total destructive interference occurs when the waves have equal but opposite displacement.
What is a stationary wave?
A wave as a result of the superposition of two progressive waves in phase with equal frequency and wavelength moving in opposite directions
How to work out phase difference?
2pi x distance/ wavelength or 2pi x time/ time period
