Waves Test - Physics

periodic (slowly) (repeated) motion:

period (T) - the time for one complete repeated pattern

frequency (f) (rapidly)

number of complete patterns per second (measured in Hz)

wave

vibration created by an initial disturbance that travels through a medium or a field

medium

the material a mechanical wave is traveling through

wave categories:

1. mechanical vs electromagnetic (gravitational)

2. pulse vs. periodic

3. Longitudinal vs. Transverse

waves transfer energy without…

waves transder energy without transferring matter

mechanical vs. electromagnetic: mechanical

needs a medium to travel through

mechanical vs. electromagnetic: electromagnetic

vibrares electric and magnetic fields, can travel through a vacuum (empty space)

Longitudinal vs. Transverse: longitudinal

the medium vibrates parallel to the direction the wave is traveling (Ex: sound)

Longitudinal vs. Transverse: transverse

the medium vibrates perpendicular to the direction the wave is traveling (Ex: light waves)

pulse vs. periodic: pulse

not repeated (becomes difficult to identify frequency or wavelength)

pulse vs. periodic: periodic (wave)

continouse wave train, with clear repeated patterns

wave ingredients: something that will vibrate

this determines wave type and wave speed

wave ingredients: an initial disturbance

this determines the wave anatomy (amplitude, wavelength, frequency and period)

physical measurments: crest

absolute highest point

physical measurments: amplitude

height measured from equilibrium

physical measurments: trough

the absolute lowest point of a wave

physical measurements: equilibrium

the resting, undisturbed state of the medium before a wave passes through it.

physical measurements: wavelength

length of one complete wave (symobl: λ)

time based measurements: frequency

frequency (f): number of waves per second (Hz)

frequency = wave/sec

time based measurements: period

period (T): the time for one wave cycle to pass (s)

period = sec/wave

time based measurements: velocity

velocity (v): speed the wave travels (m/s)

resonance

when multiples of ½ wavelength fit into the size of the object you get large amplitude vibrations

only changing the MEDIUM can ….

only changing the MEDIUM can change the wave velocity

V=λf makes it look like frequency increases velocity, but this isn’t true becuase..

V=λf makes it look like frequency increases velocity, but velocity is actually the constant

speed of sound

in air: about 342m/s (Exact depends on temp)

speed of electromagnetic waves

in vacuum (or air): 3×10^8 m/s

T=

T= sec/wave

f=

f = wave/sec

the speed of the wave refers to

how far a given point (ex: crest) on the wave travels per unit of time

two equations that can be used to detmine speed of a wave

v=d/t and v=fλ

the velocity of a given type of wave is determined by

the velocity of a given type of wave is determined by the medium

in the equation v=wavelentght (f) what happens

frequency increases, wavelength decreases and

frequency decreases, wavelength increases

how do we see things? light travels from objects to eyes, so objects either

how do we see things? light travels from objects to eyes. Objects either: give off thier own light or reflect light.

sound - what do we hear?

sound:

velocity: constant for all sounds (in a given medium)

Pitch:

frequency: high f, high pitch and low f, low pitch

wavelength: long wavelength, low pitch and short wavelength, high pitch

period: long T, low pitch and short T, high pitch

volume:

amplitude: large A - loud and small A - quiet

light - what do we see?

light:

velocity: constant (in a given medium)

color or type of light: frequency, wavelength, period

brightness or intensity:

amplitude: large A, bright and small A, dark

(when you get to the quantum scale, frequency determines energy)

visible spectrum

red- long wavelength, low f

violet- short wavelength, high f

electromagnetic spectrum (biggest to smallest wavelength)

radio, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays

wave behavior: what things do waves do and how does it change the wave

reflection, superposition (constructive/destructive interference and interference patterns like beats/double slit, standing waves), diffraction, refraction, doppler effect

reflection

some of a wave will bounce backward when it reaches a new mediun

reflection: changes

reflection changes: direction and amplitude

reflection: stays the same

reflection stays the same: medium, speed, frequency, wavelength, period

reflection examples

happens with string/slinky, waves in water, echos for sound, and mirrors for light

when waves collide, do they pass through each other or bounce off?

all waves pass through each other

superposition

waves can overlap. This can cause constructive interference (adding up) or destructive interference (canceling out).

superposition: changes

superposition changes: amplitude

superposition: stays the same

superposition stays the same: medium, velocity, frequency, wavelength, period

superposition examples

constructive and destructive happen with string/slinky, both happen with water waves

sound: constructive-more people talking and sound gets louder, destructive-noise cancelling headphones

light: constructive happens (more light is brighter) and destructive happens with single slit result

beats

beats-interference pattern

beat frequency=frequency difference

standing waves

reflection-waves bounce back off the end of the string

interferecne-incident and reflected waves interfere

node

always destructive

antinode

maximum constructivr

interference patterns: standing waves

standing waves: reflection, interference, nodes/antinodes, harmonics

interference patterns: double slit

double slit: diffraction and interferece

diffraction

waves bend around a new medium, and spread through openings. (smaller opening/larger waves=more diffraction)

diffraction changes:

changes diffraction: direction and amplitude

diffraction stays the same

stays the same diffraction: medium, speed, frequency, wavelength, period

examples for diffraction

doesn’t happen with string/slinky

in water it defracts around rocks, going through an opening and spreading out

sound can go through doorway and spread out

for light radion waves can bend over obstacles

constructive interference

when two or more overlapping waves meet in a way that their crests and troughs perfectly align

destructive interference

where two or more waves meet and combine, causing their displacements to cancel wach other out. results in a wave with a smaller amplitude than the individual waves.