Waves Flashcards
what is a progressive wave?
waves that transfer enery (from one point to another)
true or falce. waves tranfer energy but not matter
True
What is a non-progressive wave?
stationary or standing wave
waves consist of pulses what is a pulse?
one pulse is the aria under one hump on a graph of a wave
what is a pulse or wave caused by?
the disturbance of a medium
true or falce. waves do not consist of matter they travel through a medium
true
what is a Transverce wave?
a wave where the direction of motion (energy transfered) is perpendicular to the direction of disturbance
what is displacment of a wave?
the difference between the x acis and the wave
what is the wavelength?
the distance between two consicitive points on a wave with the same orientation
what are crests and troughs?
a crest is the highest point of the wave and a trough is the lowest point of a wave
what is the amplitude?
the maximum displacement
what is wavelength mesured in?
meters
define Frequency (f)
the number of complete ossolations/cycles per second (messured in Hz)
define Period (T)
Time Taken for one complete cycle/oscillation (messured in seconds)
what is period equal to in terms of frequency
period = 1/frequency
T = 1/f
what is frequency equal to in terms of period
frequency = 1/period
f = 1/T
how do yo find speed of a wave?
V = wavelenght x frequency
define phase difference
by how much (degrees, rad or wavelengths) one point on a wave is ahead of another
or
one wave is ahead of another
true or falce. to calculate the phase difference between two waves they must have the same frequency
True
true or falce. for two waves to be in phase there crests troughts and x axis intersections must all happen that the exact same time
True
what is an inverce wave
the reflection of a wave across the x axis
in a cathode ray ocilliscope (CRO) what does the y axis represent?
the voltage or current
in a cathode ray ocilliscope (CRO) what does the x axis represent?
time
what is one block on a cathode ray ocilliscope (CRO)?
one time base (messured in millie seconds)
what is intencity deffinition?
the amount of energy per unit time that passes through a unit aria
Intencity = power/aria
what is intencity proportional to?
Aria^2 or Frequency^2
define a sperical wave
a wave from a point sorce which spreads out equaly in all directions
Intencity = power/(4 pi r^2)
what are some examples of transverse waves?
electromagnetic waves: radio, visible light, UV
vibrations on gituar string (not sound)
can be shown on rope
can transverce waves be polorised?
yes
what do longatudinal waves have instead of crests and troughs?
rarefactions and compressions
true or falce. all waves can be difracted
True
can longitudinal waves be polorised?
no
give two examples of longaudinal waves
sound and ultrasound
define the doppoler effect/shifft
when the percived frequency or pitch of a wave (sound or ligh) is different to the actual frequency emitted due to the relative motion of the observed and/or sorce
what will you hear when a car is speeding towards you and why
you will hear an increce in pitch due to the sound waves being compressed in front of the car (more ossilations reaching you per second (Hz))
what will happen when a car speeds passed you and why
after the car passes you the pitch will drop drasticaly as the waves now expand towards you (less ossilations per second(Hz))
what is the equation for the doppoler effect?
observed frequency = sorce frequency (wave velocity / (wave velocity +- sorce velocity))
ROYGBIV is the visible light on the electromagnetic spectrum. what does it stand for?
Red
Orange
Yellow
Green
Blue
Indigo
Violate
does wavelength increce towards the red end of the electromagnetic spectrum?
yes
does frequency increce towards the blue end of the electromagnetic spectrum?
yes
what are proporties of electromagnetic waves?
all transverce
can travel in vaccume
travel at 3x10^8 m/s (speed of light)
they are self propogating (dont need a medium)
What is the wavelength and frequency of the first harmonic (fundamental) wave in a closed Columb? and how many nodes and anti nodes does it have?
wavelength: 2L
Frequency: C/2L
2 Nodes (one at each end) and 1 antinode
what is the wavelength and frequency of the second harmonic wave in a closed columb? and how many nodes and anti nodes does it have?
wavelength: L
Frequency: c/L
3 nodes and 2 anti nodes
what is the wavelength and frequency of the third harmonic wave in a closed Columb? and how many nodes and anti nodes does it have?
wavelength: 2L / 3
frequency: 3c / 2L
4 nodes 3 anti nodes
True or false. the n-th harmonic has n-antinodes and n+1 nodes
True
explain the principle of superposition
when two or more waves meet the resultant displacement is the vector sum of the displacement of the individual waves
state the equation for superposition
where: A = amplitude
A1 + A2 = A-resiltant
true or false. all types of waves including transverse and longitudinal can undergo super position
True
define polarization
when a wave is forced to only oscillate in one plain only due to a screen
regarding waves in an air column, what will happen if one or the ends are open
an antinode will form at any open end
what does a lower harmonic do to the frequency and pitch of a wave
lower harmonic means lower frequency and lower pitch
state Malus’s law
I = I1 cos^2 (x)
Where:
I = intensity of light through the analyzer
I1 = intensity of polarised light
x = angle between transmission axis and polariser
define interference in therms of waves
when two waves meet the resultant displacement (amplitude) is the sum total of the individual displacments
when does constructive interference occur?
when the waves are in phase
when does deconstructive interference take place?
when waves are in antiphase
true or false microwaves undergo two-phase interferance
True
what does the path diff equal for constructive interference?
path diff = n wavelenth
what does the path diff equal for destructive interference?
path diff = (n + 1/2) wavelenth
define coherance
waves with the same frequency and constant phase difference
does a lamp produce coherent light?
yes
define diffraction
the bending and spreading out of a wave when it encounters an obstacle or gap in obstacle
true or false when the wavelength is bigger than the gap we have more diffraction
true
true or false when the wavelength is smaller than the gap we have less diffraction
True
True or false diffraction only effects the amplitude of the wave
True
what is diffraction?
the bending and spreading out of waves
what is a diffraction grating?
an optical instrument used to cause a diffraction pattern when it diffracts monochromatic light into bright and dark fringes
what does a diffraction grating consist of?
a large number of very thin equally spaced parallel slits carved into a glass plate
true or false. in a diffraction screen points of maximum interference are also points of maximum intensity
True
what is the diffraction grating equation?
d sin(x) = n (lambda)
Where:
d = spacing between slits
x = angular separation between the order of maxima (degrees)
n = order of minima (1, 2, 3, …)
lambda = wavelength of light source
