ICP Chapter 15

Waves/Sound

wave

wave

a rhythmic disturbance that carries energy (NOT matter)

medium

the matter that the wave travels through

mechanical waves

must have a medium (ex: sound)

electromagnetic waves

do not need a medium (ex: light)

transverse wave

the particles of the medium vibrate perpendicular to the direction of the wave (ex: light, “the wave” in a stadium)

longitudinal wave

particles of the medium vibrate parallel to the direction of the wave (ex: sound, slinky)

wavelength

distance from a point on a wave to the same point on the next wave (abbreviated by lambda)

amplitude

distance from rest position to crest OR trough

what is amplitude determined by?

the amount of energy in the wave

frequency (f)

number of waves to pass a given point

frequency units

waves/second = Hertz(Hz)

period (T)

the time for 1 wave to pass a given point

period units

seconds/wave

wave equation

lambda*frequency

reflection

bouncing off of a wave at a barrier

normal

imaginary line perpendicular to the barrier at the point of reflection

angle of incidence (i)

angle from the incident wave to the normal

angle of reflection (r)

angle from the reflected ray to the normal

law of reflection

i = r

refraction

the bending of a wave as it passes from one medium to another

what happens when a wave changes mediums?

it changes speed

diffraction

bending of a wave around the edge of a barrier

interference

ability of 2 or more waves to add together to form 1 new wave

constuctive

makes new wave with a larger amplitude “in phase”

destructive

cancellation “out of phase”