Why do sine waves define pure frequency?

Bulle

Did anyone mention that triangle, square or any other form of waves are made up of higher frequency sine waves? In sound tech school i learned that a square wave is not really square since the change from positive to negative values in a true square wave would have to happen in absolute 0 time.

sophiecentaur

Quote by DrZoidberg

Photons also show clearly that sine waves are the most natural waveform to use as a basis. If you have a large number of identical photons, lets say with a wavelength of 1 meter, all of which have the exact same energy, and you then send them towards an antenna, they get absorbed and produce an ac current in the antenna that follows a pure sine wave.

You have this the wrong way round. 'Photons' don't explain the analysis of a function that changes with time in terms of sine waves. A photon isn't 'a sine wave' it is an amount of Energy associated with a, EM wave of a certain frequency. Photons are not all identical - even the ones from a laser or a Radio transmitter sending CW have a finite distribution of energy states. You are referring to coherence here - which, again, is not to do with transformations between time and frequency domains.
Read what people in the thread have said about orthogonal functions, for the right answer to the OP.

Similar Threads for: Why do sine waves define pure frequency?
Thread	Forum	Replies
What are the frequency bounds of waves from sine wave additive synthesis?	General Math	2
Pure Sine Wave Inverter	Electrical Engineering	5
Pure Sine Wave Inverter design	Electrical Engineering	16
Bidirectional pure sine wave inverter	Electrical Engineering	2
How do I define a sine wave?	Introductory Physics Homework	2

Bulle	Why do sine waves define pure frequency? Did anyone mention that triangle, square or any other form of waves are made up of higher frequency sine waves? In sound tech school i learned that a square wave is not really square since the change from positive to negative values in a true square wave would have to happen in absolute 0 time.