AQA A-Level Physics Summary - Optics

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Optics
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Last edited time @January 7, 2024 6:09 PM

Superposition
The vector addition of 2 or more waves to produce a single waveform.
Three examples of superposition phenomena include:

Standing waves/stationary waves - associated with musical instruments

Interference patterns - 2 source situations.

Diffraction patterns - including evidence for the wave behaviour of
particles such as electrons. Quantum phenomena

Stationary waves
The superposition of 2 waves that are in phase but travelling in opposite
directions.




Optics 1

, This common amongst strings and is how stringed musical instruments
work.

The equation of vibrating strings
f =frequency of the 1st harmonic
1 T [Hz]
f=
2L
​ ​ ​




μ
L =length of the string [m]
T =tension in the string [N]
μ =mass per unit length [kgm−1 ]

We can make some derivations using the units and v = fλ.
2λ T
This is because λ = 2 with the first harmonic. This means that
​ v= μ .
​ ​




2 −2
This is because the units of T and μcancel to give m s which when
rooted gives ms−1 , hence velocity.



Optics 2

, Interference
Single slit diffraction




Intensity diagram for single slit diffraction




Optics 3