Diffraction Flashcards
What is diffraction
When a wave curves around an object or gap
If gap is similar to wavelength then it’s diffraction is…
High
If gap is bigger than wavelength then it’s diffraction is…
Little
What is constructive interference
When two waves arrive in phase and their displacement is added together
What is destructive interference
When two waves are out of phase and so cancel each other out to give 0 displacement
What is young double slit experiment
A double slit after a single slit and then a screen to show the interference
What is the fringe
The alternating constructive and destructive wave on the screen
What is fringe spacing
The distance between two destructive waves
How to work out fringe spacing
Wavelength x distance to screen / slit spacing
The principle of superposition
When two or more waves meet, the total displacement at any point is the sum of displacement that each individual wave would cause at that point
The rules for the principle of superposition
- Applies to all waves and depends on the phase difference on the waves involved
- This in turn depends upon the path difference and that is how far a wave has travelled
Two in-phase waves path diff equation
N λ
Two out of phase waves path diff equation
(N+1/2)λ
How is there destructive and constructive waves with a single slit
Because of secondary wavelets
Who’s theory was about secondary wavelets
Huygens theory
What is different about the middle fringe compared to other fringes with a single slit
Twice the width
The further apart means the wavelength is..
Bigger
What are the distances with a single slit
The same
What’s the equation for a single slit
N λ=dsin0
What is n in equation n λ=dsin0
Which dot
What is d in equation n λ=dsin0
Split spacing
How to work out split spacing in n λ=dsin0
1 / y lines per m
