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waves questions

1. polarising filters absorb all other planes of light apart from eh one they transmit, doesn't that mean the overall intensity of the light decreases?
2. is there a reason why the natural frequency of something is the 1st harmonic? does the resonance of a material= its first harmonic?

thank you!!! this is just a bit confusing x
(edited 3 years ago)
also, my teacher during a microwave polarisation experiment that the grid thing that polarises it, the lines of the grid are further apart than in a polarising filter for light cuz microwaves has a greater wavelength. but why does this mean the grid lines are further apart like: I I I I for microwaves but for visible light its IIIIII
sorry for the amount of questions, but in my notes it says: The superposition of waves from two sources can usually only result in an observable fixed (stationary) interference pattern if the sources are coherent. This means that the waves from the sources have both the same frequency and the phase difference between them is constant..
does this mean that sometimes the phase difference isnt constant? i thought phase difference is always constant....
1) yes the overall intensity of the light decreases (what have you read that suggests otherwise?)
2) not sure what you mean here
3)
4) the phase difference between coherent waves is always constant yes, but it isn’t between non-coherent waves.
Original post by GabiAbi84
1) yes the overall intensity of the light decreases (what have you read that suggests otherwise?)
2) not sure what you mean here
3)
4) the phase difference between coherent waves is always constant yes, but it isn’t between non-coherent waves.

thank you very much <3

so in non-coherent waves, how can the phase different change? doesn't that mean the properties of the wave itself changes completely?
Original post by vix.xvi
1. polarising filters absorb all other planes of light apart from eh one they transmit, doesn't that mean the overall intensity of the light decreases?
2. is there a reason why the natural frequency of something is the 1st harmonic? does the resonance of a material= its first harmonic?

thank you!!! this is just a bit confusing x


Some extra info for Q1.
If unpolarized light passes through a polarizer, the intensity of the transmitted light will be 1/2 of what it was coming in.
Why? Here is an explanation.
https://physics.stackexchange.com/questions/113564/why-does-the-intensity-of-unpolarized-light-reduce-to-half-after-passing-it-thro

If linearly polarized light passes through a polarizer, the intensity of the light transmitted is given by Malus' law.
http://www.physicshandbook.com/laws/maluslaw.htm

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