Physics 5 - Waves and Optics Flashcards
transverse wave?
displaces up and down
longitudinal wave
<–>
wave velocity equation?
v=f*λv= velocity, f=frequency,λ=wavelength
definition of wavelength?
distance from any point where wave repeats itself
definition of frequency?
of wavelengths that pass a fixed point per secondUnits: Hzdetermined by SOURCE
definition of period?
reciprocal of frequency, it is time taken for wave to move 1λdetermined by SOURCE
wave velocity depends on
medium density and medium inertia
relative velocities of sound?
Sold>liquid>gas
decibels(dB)
log scale, for increase of 10 dB, add another exponentEx: 10-30 dB = 100 fold increase(10^3)
what is resonance?
when natural frequency and driving frequency match. = max vibration and max amplitude
what is pitch?
correlates to frequency, higher pitch=higher freq.
what is an antinode?
area of max displacement. found in standing waves/causes string to vibrate at natural/resonant frequency
what is attenuation/damping?
causes decrease in freq and velocity. results in decreased intensity of wave
Doppler Effect
change in perceived frequency when wave source and observer are moving. together = higher f, further=lower f
doppler equation
observed freq=Source freq.*(C±Vo)/(C±VS)Δfreq/source freq=v/c andΔλ/λsource=v/cwhere v is relative speed of source/observer and c is speed of wave in the mediumobserved freq=source freq±Δfreq or λo=λs±Δλif moving closer together, add source freq andΔfreq or subtractΔλ fromλs
in what direction does a moving photon (light) displace the E field and Magnetic field?
perpendicularly to eachother
equation for energy of a photon?
E=hfdirectly proportional to its frequencyh is Planck’s constant 6.64e-34
visible light range (in nm?)
390nm-700nm
visual spectrum?
infrared ROYGBIV ultravioletlongerλ<–> shorter λ
what is the speed of light?
3e8 m/s (usually represented by c)
definition of reflection?
light/wave bounces back at angle = to angle of incidence
definition of refraction?
when light/wave bends towards the normal
what is index of refraction?
n=c/vdetermines how light travels through the medium
snell’s law?
n1sintheta=n2sintheta2
what is dispersion?
when all light scatters
what is diffraction?
light/wave bends around an object
what is the focal point?
where real or virtual light rays converge
what is focal length?
distance between mirror/lens and focal point=1/2 radius of curvature
equation for lens power?
determined by focal length,P=1/funits: diopters: m-1
what does a converging mirror/lens do?
reflects light to converge at point in front of mirror/opposite lens
what is a diverging mirror/lens?
reflects light so perceived image is on opposite side of mirror/lens from observer
converging lens/mirror characteristics?
real, inverted, on the same side, and +”I am positive that the image is real and inverted
diverging mirror/lens characteristics?
virtual, upright, opposite, and (-)
special object distance rules for convergers?
if object d> focal point: image is real invertedif object d<focal point: image is virtual and upright
thin lens equation?
1/f=1/do+1/di
virtual images always have _ sign
negative
real images always have a _ sign
positive
converging lens always have a _ focal length sign
positive
diverging lenses always have a _ focal length sign
negative
the object distance is positive when
it is on the “right side”
what is the sign for a real image distance?
positive
what is the sign for a virtual image distance?
negative
equation for magnification?
M= -di/do=hi/hofor multiple lens systems, magnification is multiplicative
the lower the index of refraction the ___ light travels
faster
what is hyperopia? and how is it corrected
farsightedness, corrected with converging lens
what are the harmonics for a pipe closed at one end?
all odd numbered
sound waves are ____ waves
longitudinal
the resolution for imaging techniques is proportional to
wavelength, (shorter is better)
what happens to the refractive index as freq. increases?
refractive index also increases
according to snells law, as n2 increases, sintheta2 must
DECREASE
what does a lower index of refraction do to the refraction angle?
inversely proportional according to snell’s law. so large refraction angle results from LOW index of refraction
shortest period = shortest____
wavelength
what is total internal reflection?
when light wave has angle of incidence greater than the critical angle
what is happening to particles in a longitudinal wave?
they are striking eachother to propogate the wave
what is the equation for frequency of a spring?
f=(1/2pi)*(sqrt(k)/m)
what is the potential energy of a spring?
PE=1/2k*deltax2
what is the wavelength of a standing wave in a closed-closed or open open space?
lambda=2L/nwhere L is length and n is harmonic
T/F, photon speed is influenced by their energy
FALSE
what do you need to utilize the doppler equation?
one of the speeds (detector or source), along with the observed and emitted frequencies
the intensity of EM radiation is directly proportional to
number of photons emitted
what is the equation for magnification?
di/do
how do you calculate the energy of a photon released from an excited electron?
subtract lower energy level from excited energy level
what does a decrease in bending do to the focal length?
increases it
how do you figure out the higher harmonic frequencies?
they are multiples of the fundamental frequency, so f2=2*f1
a negative focal length indicates
DIVERGING lens
what is the fundamental frequency of a vibrating string?
f=v/2L
what kind of lens is required by nearsighted people?
diverging, because the focal length is too short and the image is focused in front of the retina
what is a plane mirror?
produces image behind its plane at distance equal to object distance in front of the plane.
