Superposition Flashcards
Superposition definition
When 2 or more progressive waves meet and overlap, they supervise, producing a single wave.
The principle of superposition states
When two waves meet at a point, the resultant displacement of the wave at that point is equal to the sun of the displacements of the individual waves.
When a wave superposes with another wave
There is a constructive interference (where the individual displacement are both in the same direction and add together) and destructive interference (here the individual displacement counteract each other as they are in opposite directions )
Two waves are coherent when they
Are emitted with a constant and unchanging phase difference
Interference is
The superposition occurring between two coherent waves
Techniques to investigate superposition for sound waves
For sound waves two audio signal generators came be used to investigate superposition. They will both emit coherent waves in all directions which will overlap and form an interference pattern. When a microphone connected to an oscilloscope is moved parallel to the speakers regione it like and quiet noise will be detected.
Techniques to investigate superposition and wavelength for light
The Young double-slit experiment can be used to investigate superposition in light, and also to determine the wavelength of the light source used. A laser which produces monochromatic light (light of a single wavelength) is placed behind a sheet with two small slits in it, a distance ‘a’ apart. The two coherent waves produced by the slits overlap and superpose, creating alternating bright (maxima) and dark (minima) fringes on a screen. The distance between two adjacent maxima is ‘x’, and the distance between the double slits and the screen is ‘d’. The equation
lambda=ax/d
can then be used to determine the wavelength of the light used. This setup and formula can also be used when investigating superposition in microwaves.
Techniques to investigate wavelength for light
The wavelength of a light source can also be investigated using a diffraction grating. The light is able to pass through the transparent slit between the scratches, and produces an interference pattern with bright and dark maxima and minima. The number of slits is usually given per cm, and this must be converted in to the value ‘d’, the distance, in metres, between each slit. The order of maxima (whether it is the original, first, second etc. bright maxima) is referred to as ‘n’, and θ is the angle between the 0th and nth maxima. The formula
dsin@=n x lambda
can then be used to determine the wavelength of the light source.
What’s a diffraction gradient
A diffraction grating is a piece of transparent material with many opaque lines scratched in to it.
What’s the difference between double slits and single slits when it comes seeing the results due to waves diffracting
Central maxima is a lot brighter compared to fringes and double the width of the fringes in a single slit.
The maximum no of orders that you can see is
n, where the nth order is at an angle less than ninety degrees from the central maxima or zeroth order
