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What is a wave?
transfer of momentum between two points

mechanical waves require what in order to travel?
medium

transverse v. longitudinal wave
transverse: medium is displaced perpendicularly to direction of wave propagation
longitudinal: medium is displaced parallel to the direction of wave propagation

sound in air is what kind of wave?
longitudinal

amplitude is always what sign?
positive

velocity of a wave is dictated by?
medium it's traveling in

what two aspects of the medium affect velocity of the wave?
 medium's resistance to change in:
 1 shape (elasticity)
 2 motion (inertia)

greater density medium makes wave travel faster or slower?
slower

heavier medium  faster or slower?
stiffer medium  faster or slower?
heaver slow waves down
stiffer mediums speed waves up

for a gas medium, velocity of the wave changes how with changing temperature?
velocity increases with temperature

do sound waves move more quickly through hot or cold gases?
hot

elastic and interial components of medium store....
elastic = potential energy
interial = stores kinetic energy

wave velocity is independent of...
frequency, wavelength, and amplitude

surface waves: transverse or longitudinal?
completely neither

intensity (what is it and units)
energy transfer per area
W/m^{2}

intensity increases with the square of?
amplitude and frequency
greater (amplitude and frequency)^{2} = greater intensity

does intensity depend on medium?
yes
density and velocity

increase area = decrease intensity: snapping fingers example
propagates waves in all directions
energy is constant, but area is over a larger sphere
decrease in intensity of the sound

intensity level measured in....
decibels (dB)

if intensity increases by a factor of 10, decibels increase by...
addition of 10 decibels
adding 2 zeros to intensity = adding 20 decibels

in phase v out of phase
in phase: same wavelength, start at same point
out of phase: travel different distances but arrive at same point

constructive v. destructive
constructive = sum results in greater displacement
destructive = sum results in smaller displacement

superposition
any wave can be created by superposition of many sine waves

beat
occurs when two waves with slightly different frequencies are superimposed

how does beat work?
some points will be nearly in phase (constructive)
some points will be out of phase (destructive)

audible beats must have close frequencies?
yes,
in other words, the two frequencies shouldn't be too far aparat

first and second harmonic have a ratio of
1:2

beat frequency is equal to:
f_{beat} = I f_{1} f_{2 }I

beat frequency is an alternating increase and decrease in....
intensity of the noise

pitch correlates to...
frequency
high frequency = high pitch

when a wave transfers from one medium to the next, does wavelength or frequency change?
frequency remains the same
wavelength changes

standing waves
node and antinodes

node
point of no displacement [in line]

antinode:
point that experiences maximum constructive interference

what is a harmonic series?
only certain wavelengths could create a standing wave

1st harmonic: how many nodes and antinodes? length of rope?
fundamental wavelength
one antinode
length of rope = 1/2(wavelength)

second harmonic
created by adding another node
two antinodes
L = 2/2 (wavelenth) = wavelength

each successive harmonic is create by
adding another node

equation for length of rope

L = (n × wavelength_{n})/2 (n = 1,2,3….)

equation for wavelenght_{n}
wavelength = wavelength/n

resonance
vibrate at is resonant frequency

how can you find resonant frequency?
velocity through a medium is constant,
 so when it resonates, its resonant frequency is
 v = (lambda)(freq.)

what does simple harmonic motion mean?
it repeats itself

what kind of function is it?
sinusoidal function of time

example of simple harmonic motion
standing in front of someone riding a bike: looks like they're peddling up and down
pendulum

equation for angular frequency
w = 2pif

in simple harmonic motion, how is acceleration related to distance?
directly proportional
but opposite signs

What relates acceleration and frequency?
square of the frequency

how does mass on pendulum affect motion?
it doesn't

period for pendulum (equation)
T = 2pi (L/g)^{1/2}

when pendulum is in the middle (straight down) KE and PE are
KE is at its maximum
PE is at its minimum

what kind of curve is the KE of a pendulum?
sine curve
(simple harmonic motion)

Hooke's law: mass hanging from a spring:
forces are greatest when? acceleration is constant?
forces are greatest when spring is fully compressed or fully extended
since F = ma, and a is also greatest
[Hooke's law: F=k x change in x

period (T) in simple harmonic motion
T = (2pi) x sq.rt.(m/k)

energy oscillates between...
KE and one or more forms of potential energy


What is an electromagnetic wave?
traveling oscillation of an electric and magnetic field

What kind of wave is what kind of wave?
transverse wave

How are electromagnetic fields generate?
acceleration of an electric charge

electromagnetic spectrum: energy and wavelength
inversely proportional:
E = hf = h(v/lambda)

electromagnetic spectrum (left to right) inc. or dec. wavelength and frequency
left to right  dec. wavelength, inc. frequency
so moving left to right = increasing energy

order of increasing energy
radio < microwaves < IR < ROYGBIV < UV rays < x rays < gamma rays

intensity of light is a measure of...
frequency of photons (photon energy stays the same)

what is monochromatic light?
light with a single frequency

index of refraction (equation)
n = c/v
 c = 3 x 10^{8}
 v = speed of light in medium

light waves travel faster or slower when propagating through a medium
slower
 index of refraction for air = 1
 other medium = greater than 1

light made of photons:
what is the electromagnetic wave?
each photon = electromagnetic wave

dual nature of light  what do each reflect?
wave = propagation properties
particle = energy transformation

angle of refraction (equation)
n_{1}sin_{1} = n_{2}sin_{2}

light's preferred path
shortest path possible

when light crosses into a new medium, what happens to frequency and wavelength?
frequency stays the same
wavelength changes

how does wavelength change, increase or decrease?
n_{2} is greater = wavelength decreases
n_{2} is less = wavelength increases
(inversely proportional)

energy of a photon
E = hf
h = 6.63 x 10^{34}

when light is refracted, while it still have the same amount of energy per photon?
yes,
just that some photons were reflected and others refracted

critical angle: what is it, and what is the equation?
all photons are reflected (none refracted)
sin^{1}(n_{2}/n_{1})

What is dispersion of light?
different light frequencies travel at slightly different speeds
(index of refraction varies with frequency)

Do longer waves or shorter waves move faster?
longer waves  lower frequency

since longer waves move faster, is there a greater or lesser bending at the media interference?
less dramatic

What is diffraction?
when a wave moves through a small opening, it bends around the corners of it
bending = diffraction

size of opening, relative to wavelength of the wave  and how will that affect bending of the wave
the smaller the hole, the greater the spreading of light
so, small opening = long wavelength = more bending

what happens when diffracted waves meet?
interference
forms bright and dark images

which produces bright and which dark images?
constructive = bright
destructive = dark

diffraction is part of light's wave or particle phenomenon?
wave

If light were purely a particle, what would happen when it moved through the slit?
no diffraction
all light would go directly to detector at the level of the slit.

mirrors and lenses: which reflect and which refract?
mirrors = reflect
lenses = refract

lenses: diverging and convergine (relative to mirror concave and convex)
diverging = concave
converging = convex
Thicker Center Converges

radius of curvature:
decrease radius of curvature is...
a sharper curve
straighter line = larger radius of curvature

what is the focal length?
focal point is separated from mirror/lens by the focal length (f)

focal length of mirror
1/2 radius

focal length of lens  affected by:
 refractive index of lens (n_{1})
 substance around the lens (n_{2})
 radii of curvature

what is the magnification
ratio of size of image/object
"dido"

magnification (equation)
m =  (d_{i}/d_{o}) = (h_{i}/h_{o})

what does negative in the magnification equation mean?
if both distance are positive, image is inverted

positive magnification means
negative magnification means
positive = upright image
negative = inverted image

thin lens equation:
1/f = (1/d_{o}) + (1/d_{i})

System for Mirrors and Lenses
1. I (eye) am positive that real is inverted

images on side of "eye" are always....
images on the other side are always...
side of eye = positive, real, and inverted
other side = negative, virtual, and upright

front and back for mirror and lens
eye is in front of mirror
behind lense

front and back  positive and negative
front = positive
behind = negative

What are negative, virtual and upright?
 convex mirrors
 diverging lenses

what are positive, real, and invert?
 concave mirrors
 converging lens

exception:
if object is within focal distance os concave mirror or converging lens: image is negative, virtual, upright

so, what is always negative
convex mirror, diverging lens

Power of lens (equation)
(1/f) = (1/d_{i}) + (1/d_{o})

