maximum phase difference between two waves

Thread Starter


Joined Apr 15, 2011

I believe the maximum phase difference possible between two waves is 90°. Suppose we have two waves. When the wave A is just starting out which means its phase is 0∏ or 2π, the wave B is at its 3∏/4 (correction: 3∏/2) phase. From wave A's perspective, wave B is lagging behind by 90° but from wave B's perspective the wave A is leading it by 90°. Would there be a difference mathematically? Perhaps, in one way, phase difference is 90° but in other way it's -90°. Please help me with it. Thanks.

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Joined Mar 6, 2009
This raises an interesting problem. Suppose you were looking at the two waves [A & B] on an oscilloscope - where they are time dependent sine functions with the same frequency.

What is the maximum phase difference you would be able to discern on the scope? As stevb & samin note, the maximum difference you could possibly see would be 180° when the two signals are in exact anti-phase.

Could you discern a difference of B leading A by 270°? Would it not simply appear to an observer that wave B leads A by 90°.

BTW PG1995: In your post you suggested a case situation where "..the wave B is at its 3∏/4 phase." Keep in mind that 3∏/4 is 135°.


Joined Feb 11, 2008
The maximum phase difference is 359.99 (repeating) degrees.
The maximum +/- phase difference is 180 degrees.