Waves Flashcards
What is a progressive wave
Transfers energy without transferring material, made of particles in a medium oscillating
Example of a progressive wave
Water waves - particles move up and down
What is the amplitude of a wave
Max displacement from equilbrium position - measured in meters
What is the frequency of a wave
Number of complete oscillations passing through a point per second - measured in Hz
What is the wavelength of a wave
Length of a whole oscillation - measure in meters
What is the speed of a wave
Distance travelled by wave per second - measured in ms^-1
What is the phase of a wave
Position of a certain point on a wave cycle - measured in radians, degrees or fractions of a cycle
What is the phase difference of a wave
Distance between two adjacent points in phase with each other - measured in radians, degrees or fractions of a cycle
What is the period of a wave
Time taken for one full oscillation - measured in seconds
When are two points completely out of phase
Odd integer of half cycles apart
Frequency, wavelength and speed formula
c = f x wavelength
Frequency, period formula
F = 1 / T
What are transverse waves
Oscillations of particles or fields at a right angle to the direction of energy transfer
Key features of electromagnetic waves
Transverse, travel at 3x10^8 ms^-1 in a vacuum
2 demonstrations for transverse waves
Shaking a slinky vertically, waves on a string attached to a signal generator
What are longitudinal waves
Oscillations of particles is parallel to the direction of energy transfer, compressions and rarefactions, can’t travel in a vacuum
Demonstration for longitudinal waves
Pushing a slinky horizontally
What sort of wave is sound
Longitudinal
Which sort of waves can be polarised
Only transverse
What are polarised waves
Waves that oscillates in only one plane (up and down or left and right)
What does polarisation provide evidence for
Nature of transverse waves, polarisation can only occur if a wave’s oscillations are perpendicular to its direction of travel (like in transverse waves)
What is proof of transverse waves
Polarisation - can only occur if a wave’s oscillations are perpendicular to its direction of travel
Application of polarisation
Polaroid sunglasses, TV and radio signals
How do polaroid sunglasses work
Reduce glare by blocking partially polarised light reflected from water and tarmac - only allow oscillations in the plane of the filter - making it easier to see