U2.1 Waves Flashcards
What is a wave
Periodic disturbances
What is a progressive wave
A wave that transfers energy from one place to another
Eg. Loud speaker to ear
What is a standing wave
A wave which does not involve the transfer of energy as the wave energy is stored in the system
Eg. A guitar string
What is a transverse wave
A wave where particles in the medium vibrate perpendicular to the direction of travel
Eg. Seismic secondary waves and all electromagnetic waves
What is a longitudinal wave
A wave where the particles vibrate in the medium parallel to the direction of travel of the wave
Eg. Sound waves, ultrasound waves and earthquake primary waves
What is the amplitude of a wave
The maximum displacement of a particle of the medium from its rest position. Unit is meters
What is the time period of a wave
The time it takes a wave to have one crest and one trough. Unit is seconds
What is the frequency of a wave
The frequency is the amount of waves that pass a point in one second. Unit is Hertz
Frequency = 1 / time period
What is wavelength
Wavelength is the distance between two consecutive crests or troughs. Unit is meters
What is phase
Describes the particular point in the cycle of a wave. One wave or one cycle of oscillation is similar to one complete rotation.
One wave / cycle = 1 wavelength = 360° = 2pie radians
What is polarisation
When transverse waves such as light are passed through a slit so that they only have one plane of vibration. This can only be achieved with transverse waves as particles vibrate adjacent to the direction of travel.
How can you adjust the intensity of polarised light
Add a second polariser known as an analyser. By rotating this the intensity will decrease or increase.
What is polarised light used for
Sunglasses- it reduces glare of reflected light
LCD displays- used to show light and dark areas
What is the electromagnetic spectrum
The range of wave lengths of which all electromagnetic waves exist
What is the order of the electromagnetic spectrum in terms of increasing wave length
Gamma rays, X-rays, Ultraviolet, visible, infrared, microwaves, radio waves.
