Waves Flashcards
How are stationary waves formed?
They are formed when 2 progressive waves with the same amplitude , frequency and phase difference travelling in opposite directions interfere with each other
How long is a wavelength in Pi
2Pi
Equation for fringe separation W=fringe separation D=distance from slits to screen s=slit spacing wavelength arrange for slit spacing to be the subject
s=(wavelength x D)/w
How are bright fringes formed
Light from one slit reinforces light from other slit
How are dark fringes formed
Light from one slit cancels light from other (light waves are 180 degrees out of phase
Equation for wavelength with c,f,λ
c/f=λ
The equation for fringe spacing
λD/S=W
What is a node?
This is points of no displacement where the nodes remain in the same position. Particles at those points are not vibrating at all and they have no energy.
The equation for Diffraction Grating
d sin(θ)=nλ
The refractive index of air
1.000277 or 1
The equation for the refractive index of a substance
n=C/Cs
Total internal reflection: sinθc = ???
n2/n1 where n2>n1
The refractive index of Diamond
2.417
Snell’s law for refraction of a boundry
n1 sinθ1 =n2 sinθ2
What are coherent sources
The light emitted is in constant phase difference and same frequency
How do you reinforce a fringe
Have wavelength arrive in phase with monochromatic light
E.G. π,2π,3π
How do you cancel the path difference
May light 180 degrees out of phase
E.G. π/2, 2π/3, 3π/4
The refractive index of Diamond
2.417
A light ray is directed into a glass block that has a refractive index of 1.5 at an angle of incidence of 40°. Calculate the angle of refraction.
sin−1(sin40/1.5)
What is the diffraction grating equation
Wavelength
Diffraction grating=d
d x sin(theta)=n x wavelength
How to calculate number of slits per metre on the grating
d = diffraction grating
N = number of slits per metre
N=1/d
sin(i)/sin(r) = C/?
C/Cs
Does the frequency change when diffraction occurs?
no or nah m8
Finish the sentence
The smaller the value of the diffraction grating the greater the ___________________________
Angle of diffraction
What are the three types of spectra
Continuous
Line emission
Line absorption
What kind of light is produced by a laser
Monochromatic
What are electromagnetic waves
Oscillating electric and magnetic fields that go through space without the need of a substance
Which waves are considered electromagnetic waves
Radio waves Microwaves Infrared radiation Light Ultra violet X-rays and gamma radiation
Do longitudinal waves move parallel or vertical and do they compress or not
Parallel
Do compress
What waves are classed as longitudinal
Sound waves
Primary seismic waves
Do transverse waves move parallel or perpendicular
They are perpendicular
WHAT IS TOTAL INTERNAL REFLECTION?
WHEN A LIGHT RAY REFLECTS OFF THE INSIDE OF A TRANSPARENT MATERIAL.
when can total internal reflection take place?
- When the angle of incidence exceeds the critical angle of the material.
- The incidence material has a larger refractive index then the other material.
why is a laser used to produce light
so that the light produced is of the same frequency
give a use of internal reflection
optical fibers
what is the layer called that covers optical fibres?
Cladding
What is an antinode?
These are points on the waveform where the particles are of a displacement and energy.
Describe what fringe pattern you would see when white light is the source of light?
You would see the colours of the spectrum and the centre is white as every colour contributes to the central pattern.the inner fringes are blue and outer are red as the red fringes are spaced out further than the blue fringes.
What is the wavelength for the first harmonic if the distance of the string is 0.30m?
It is 0.60m because the first harmonic is half of the wavelength. (Use equation λ1=2L)
What is the wavelength for the second harmonic if the distance of the string is 0.60m?
It is 0.60m because the second harmonics wavelength is equal to the distance of the wire. (Use equation λ2=L)
What is the wavelength for the second harmonic if the distance of the string is 3m?
It is 2m because the third harmonic is two thirds of the distance of the string.(use equation λ3=2/3L
What happens to the wavelength as you increase frequency of a stationary wave?
The wavelength also increases.
What is a coherent source?
It is a source with a constant phase difference and the same frequency.
what is slit separation?
It is the distance between the end of i slit and the end of the other or middle to middle or begging to begging.
When dark fringes are formed what type of interference is this?
Destructive interference.
What safety precaution is needed when using a laser?
Never look directly into the light.
Which waves are transverse
Electromagnetic
Secondary seismic
Waves on string or wire
How do you know if a transverse wave is plane polarised
When vibrations stay in one plane only
How do you know when a wave is unpolarised
When the wave moves to a different plane
dark fringes are made when light , with a phase difference of Pi apart, meats each other. is this true or false?
true
What is an example of making a polarised wave
Having a wave on a string go through a slit In a board
Use of polarising light in real life
Sunglasses
What happens if polarised light passes through a Polaroid at 90 degrees to the polarised light
It won’t go through
What is the definition of displacement of vibrating particles
It’s distance and direction from equilibrium position
What is the amplitude of a wave
Maximum displacement of a vibrating particle
What is the wavelength
Least distance between two adjacent vibrating particles with the same displacement and velocity
