amplitude
maximum displacement of a point on the wave from it’s undisturbed position
wavelength
the length measured from one point of a wave to the next adjacent point *
frequency
number of complete waves passing a certain point per second
Hertz, Hz
period
time taken for a full cycle of the wave
(think period of time)
transverse waves
have oscillations perpendicular (90*) to the direction of energy transfer
eg. light waves
longitudinal waves
have oscillations parallel to the direction of energy transfer
eg. sound waves
wave speed =
frequency x wavelength
Speed of sound practical
- both microphones next to speaker, slowly move one away until 2 waves aligned but have moved exactly 1 wavelength apart
- measure distance between microphone = 1 wavelength
- use formula
Speed of water ripples practical
- dim lights, turn on lamp should see waves as shadows below tank
- distance between each shadow line = 1 wavelength
- measure distance between shadow lines 10 wavelengths apart - divide by 10 = average wavelength
- use formula
Waves on strings practical
- turn on signal generator and vibration transducer
- adjust frequency of signal generator until clear wave on string (frequency needed depends on length of string between pulley and transducer, and the masses used)
- measure wavelength
- frequency = what signal generator is set to
- use formula
Measure wavelength (waves on strings practical)
- measure length of (eg) 4-5 wavelengths in 1 go
- divide to get mean half wavelength
- double this mean to get full wavelength
- watch video on this
All waves can be… (3)
Absorbed
Transmitted
Reflected
Electromagnetic Waves (EM waves)
Vibrations of electric and magnetic fields
Transverse waves
EM waves speeds
- travel at same speed through air or vacuum
- travel at different speeds in different materials
Our lines can only detect _____ of EM spectrum
Visible light
What is EM spectrum grouped based on
Wavelength and frequency
refraction
waves changing direction at a boundary
rays
staight lines that are perpendicular to wave fronts
show the direction a wave is travelling
if a wave slows down…
it bends towards the normal
if a wave speeds up
it bends away from the normal
optical density of a material
a measure of how quickly light can travel through it
what happens when a wave refracts
it’s wavelength changes
it’s frequency stays the same
oscillations
repeated regular back and forth movements about a central equilibrium position
