what are waves?
vibrations that transfer energy without net movement of matter
wavelength
length of full cycle of a wave
amplitude
displacement from rest
or maximum disturbance from undisturbed position
frequency
number of full waves passing a fixed point per second
unit of frequency
hertz - Hz
formula for frequency and time period
f = 1/t
T=1/f
formula for wave speed
frequency x wave length
types of waves
tranverse
longitudinal
tranverse wave
vibrations are perpendicular to direction of energy transfer
longitudinal wave
vibrations are parallel to energy transfer
examples of transverse wave
- light
- EM waves
- S waves
- slinky spring up and down
examples of longitudinal wave
- sound
- P waves
- slinky spring pushed
law of reflection
i=r
how does reflection affect wave properties?
- does not change speed wavelength or frequency
how does refraction affect wave properties?
- changes speed and direction
- does not change frequency as comes from outside source
what is ultrasound?
high frequency sound wave >20,000 Hz
uses of ultrasound
- sonar: ships use ultrasound to locate fish
- medical imagine: pregnant women
- removing kidney stones: vibrations break up stone
- animals: locating prey
what is doppler effect?
change in frequency and wavelength
- source moves towards source - high frequency, short wavelength - high pitch
- source moves away from source - low frequency - long wavelength - low pitch
