chapter 11/12 - waves Flashcards
mechanical waves
energy is transferred by vibration of particles carrying the wave through a medium eg sound seismic water
longitudinal waves
oscillate parallel to the direction of energy transfer
transverse waves
oscillate perpendicular to the direction of energy transfer
amplitude
max displacement from undisturbed position
wavelength
distance between two adjacent points on the same cycle of a wave
frequency
number of complete oscillations / time
displacement position graphs
give a snapshot of what a wave looks like at a point in time
- to find which direction each part is moving draw the wave slightly later
speed
freq * wavelength
phase
is the fraction of a cycle it has traveled since the start of the cycle - always and angle in rad
1 cycle = 360 or 2𝞹
phase difference
difference in degrees/ rad / angle between points on the same wave or similar points on 2 waves
- fraction of the cycle that passes between 2 maximums
one complete cycle
2𝞹 = 360
in phase
two waves at the same point in the cycle
phase difference = 2pi or 360
antiphase
two waves doing opposite things at the same point
phase difference = pi or 180
coherent
waves with constant phase difference
must have the same freq to make phase diff constant
interference
the superposition of coherent waves
principle of superposition
when waves are at the same point there resultant displacement is = to the sum of individual displacements
CRO traces
amplitude - count squares * volts
time period - count squares * time base
frequency - 1/T
progressive wave
transfers energy from one point to another
phase difference equation
phase difference = 2pi d/ wavelength
phase diff/ 2 pi = d/ wavelength
intensity
radiant power per unit area
Power/ Area
- radiates equally in all directions I = P/ 4pi r^2
(inverse square law)
intensity is proportional to
KE
v^2
A^2
v is proportional to A
refraction diagram
- incident ray
- normal
- angles
- emergent ray
- refracted ray
- direction arrows
- change of direction
- title
reflection
wavelength is same because speed doenst change
refraction
wavelength decreases if speed decreases as f stays same