Waves Flashcards
What is a transverse wave
Propagation is perpendicular to direction of energy transfer, no need of medium
What is a longitudinal wave
Propagation is parallel to direction of energy transfer, needs a medium
Examples of transverse waves
Light, secondary seismic waves, waves on a rope
Examples of longitudinal waves
Sound waves, mechanical waves
What is plane polarised
When oscillations of a wave are in only one plane, perpendicular to direction of energy transfer
Examples of unpolarised light
Candle or filament lamp
When is light intensity at minimum if two polaroid filters are placed between light
Filters are crossed at 90 degrees
Uses of polaroids
Polaroid glasses to reduce glare from glass (drivers)
What is amplitude
Maximum displacement from equilibrium position
What is wavelength
Length of a one whole wave cycle
What is a period
Time for one wave cycle to pass
What is frequency
Number of wave cycles per second
What is phase difference
Fraction of a cycle between the vibrations of the two particles on a wave, measured in radians or degrees
Do waves travel faster or slower in shallow water
Waves travel slower in shallow water
When is diffraction at its optimum
When the gap is closest to the wavelength of the wave
What is superposition
When two waves meet, the total displacement is equal to the sum of displacements from each wave
What is a stationary wave
A wave that doesn’t transfer energy, formed when two progressive waves pass through each other of same wavelength, composed of nodes and anitnodes
What are nodes
Points on a progressive/stationary wave with 0 displacement
When does interference occur
When waves of constant frequency and phase difference passes through each other
Examples of stationary waves
Formed on string, microwaves and sound waves
What are antinodes
Maximum amplitude between nodes
What is unpolarised light
Light with oscillations in many different directions, perpendicular to direction of energy transfer
Reflected light are…
Plane-polarised
How are stationary waves formed on a string
Waves of the same frequency and wavelength reflect of one side. Waves now travelling in opposite directions interfere
What is a progressive wave
Wave that transfers energy from one point to another
What must be satisfied about a string fixed on both ends for a stationary wave
L = n X (lambda/2)
Explain why the minimum intensity between the 2 and 3 maximums is not zero
Intensity decreases with distance, one wave travels further than the other, amplitudes are not equal to each other
What occurs when the width of the slits are increased
The intensity of light increases
With reference to resonance, why does changing the length affect the loudness of the sound
Air has a natural frequency of vibration, when the fork frequency equals the natural frequency of vibration maximum loudness, when they are not equal volume drops
How to find phase difference in a STATIONARY WAVE
0 if particles are between adjacent nodes or separated by an even number of nodes.
180° if the two particles are separated by an odd number of nodes.
Which electromagnetic wave has a wavelength, similar to the diameter of a nucleus
Gamma
What changes when light refracts
Speed and wavelength
What condition is necessary for interference to be observed
Constant phase difference
Describe the motion of a particle on a transverse wave
Perpendicular to direction of energy transfer (then talk about up, down directions)
