Waves Flashcards
Displacement (x)
Distance moved by a particle or field in a specific direction from a fixed point
Amplitude (X₀ or A)
Maximum displacement from equilibrium position
Period or Periodic Time(T)
Time taken for one complete oscillation/cycle/revolution
Frequency (F)
Number of oscillatons per second
Frequency formula and unit
f= 1/T (one over period)
Hz or s−1
Angular frequency (ω)
rate of change of Angular displacement
Angular frequency formula & unit
ω= dθ /dt = 2π/ T = 2πf
rads⁻¹
Wavelength (λ)
Distance between two successive wave crest or trough or two consecutive particles in phase
λ=
& units
v/f
m
velocity in waves
rate of change of displacement with time
velocity in waves formula
v=λ/T
v=λf
phase
angle in degrees or radians that give the measure of the fraction of the oscillation that has been completed by the wave
Phase difference
The measure in degrees or radians of how one wave is out of step with another
Phase difference formula
Φ=y/λ by 2π
where y is the path difference
What type of interference do you get when two wave are in phase
constructive interference (no phase diff, or whole num phase diff λ, 2λ,…)
What type of interference do you get when two wave are out of phase
destructive interference(1/2λ, 3/2λ)
path difference is the
extra distance in wavelengths that one wave travels compared to another wave
basically the difference in distance travelled from the same point
half a wave length path difference is equal to… and whole number path diff (eg 1) is equal to…
180 degrees phase difference
0 degrees path difference
the speed (v) of a wave is
the rate at which energy is being transferred
Waves are
travelling/propagating disturbances that transmits energy from one point to another, through a medium without transferring the medium/substance
Mechanical wave are
waves that need a material medium to propagate through
what are the types of mechanical waves
longitudinal and transverse
In transverse waves particles oscillates
at right angles to the direction of energy transfer
In a longitudinal wave particles oscillates
TO an FRO in the same direction as the energy transfer
A longitudinal wave has a series
of compressions and rarefactions
compressions is the region where the particle move towards eachother and rarefaction is the region where they move away from eachother
Examples of longitudinal waves
sound waves. ultrasound waves and seismic P-waves.
Examples of transverse waves
ripples on the surface of water.
vibrations in a guitar string.
a Mexican wave in a sports stadium.
electromagnetic waves – eg light waves, microwaves, radio waves.
seismic S-waves.
progressive wave is
a wave that transfers energy from from the source to areas around it
Standing/Stationary wave is
a wave the is NO NET ENERGY transfer in space but in time shows an interchange between Kinetic energy and potential energy as a result of superposition
Intensity of a wave
the rate at which it transfers energy (power incident per unit) divided by the area over which the energy is spread. that is P/A or E/At
Intensity of is proportional to
(intensity formula & units)
the Amplitude squared
I∝A² or I∝ xₒ²
I=kA²
Wms⁻²
A² = 1/r²
Polarization definition
polarization is the restriction of oscillations to ne plane
In an unpolarized wave the oscillations
are in various planes and not restricted to one plane
Which waves can polarized and which ones cannot
transverse waves can b polarized since the oscillate in right angles giving my angles to move through and longitudinal waves travel parallel to propagation
What is used to distinguish between longitudinal and transverse waves
Polarization since transverse waves can be polarized and not longitudinal waves
Superposition DEFINITION
The combining or 2 or more similar waves hen the meet at a point
Superposition principle
the resultant displacement of two or more waves that meet at a point is found by algebraic sum of each wave (when in phase, when out of phase subtract)
Wavefront definition
The surface joining all wavelets which are in phase
Diffraction definition
the spreading out of a waves’ wavefronts when the pass through a gap or edge of a surface, without altering its wavelength
Inorder for diffraction to be observed
the wavelength of the wave must be comparable to the width of the gap
single slit diffraction formula
dsinθ=nλ
where d -separation of gratings /m
θ-angle between zeroth order fringe and nth order fringe
λ- wavelength of light /m
n - nth order fringe
interference
is the result of superposing two or more waves from a finite number of waves
coherent waves definition
waves have the same frequency or wavelength, constant phase difference/relationship & roughly same amplitude
To produce coherent light sources in young’s double slit experiment what must be done…. then?
a single slit must be used. Then as the light passes through the double slit, diffraction takes place and the light over laps
Explain the double slit experiment
At points where the crests of waves coincide, constructive interference
occurs. These points correspond to bright fringes on the screen. At points where crests and troughs coincide, destructive interference occurs. These points correspond to dark fringes on the screen. In both cases, the waves are superposed.
5 Conditions for (perceptible ) interference
waves must meet at a point or overlap superpose and must be coherent
transverse wave must be polarized or unpolarized in same plane
same type of mechanical wave
Conditions for (complete constructive ) interference
path diff=whole number or wavlengths
Conditions for (complete destructive ) interference
path diff=odd number of waves
wave equation
Asinωt
tanθ in interfernce
tanθ=y/d in rads
optical path
the path in a medium that nt whe
wavelength of light formula
λ=ax/D
x=fringe separation
λ-wavelength of light/m
D-perpendicular distance between the screen and the double slits/m
a – the separation between the slits/m
wavelength of monochromatic light formula
λ =d sinθ/n
λ – wavelength of monochromatic light/m
d – distance between slits/m
θ – angular deviation for the nth order
n – nth order diffracted light
The wavelength of a
monochromatic light source can
be determined
experimentally
using Young’s double slit
experiment.
The wavelength of a
monochromatic light source can
be determined
experimentally
using a diffraction grating.
SHM is a periodic motion in which:
1 the acceleration is proportional to the
displacement from a fixed point and
2 directed towards the fixed point.
a =
a – acceleration/ms–2
ω – angularfrequency/rads–1
x – displacement/m
–ωsquaredx
refractive index
sin i /sin r
snells laws
1n2 = sin i/sin r
The specific heat capacity of a
substance, c,
is the amount of heat
energy required to increase the
temperature of one kilogram of a
substance by one degree.
EH=
EH– amount of energy absorbed
m – mass/kg
c – specific heat capacity/J kg–1K–1 or J kg–1°C–1
Δθ – change in temperature/K or °C
= mcΔθ
or CΔθ
OR mlv lv-ltent heast of vapri…
or mlf
heat capacity C=
mc mass x specific heat capacity
The specific latent heat of fusion lf
is
the energy required to convert 1 kg
of substance from a solid to a liquid
without a change in temperature.
The specific latent heat of
vaporisation lv
, is the energy
required to convert 1 kg of substance
from a liquid to a vapour without a
change in temperature.
