# Phase difference and Standing waves vs Progressive waves

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1. May 18, 2017

### Lamar Ngolo

and 1. The problem statement, all variables and given/known data
Ok, so I am doing As physics at the moment and have been left confused by stationary waves.
I have read that between adjacent nodes/ even numbers the phase difference is always 0 and between numbers of does it is pi radians. So in the attatched image why is my textbook giving answers of 180, 225 and 0 degrees: this is what would be the case on a progressive wave, right?
Also, do stationary waves only form where 2 progressive waves in opposite directions have the same frequency, wavelength and constant phase difference, or only a few of the named conditions needed?

Thanks everyone

2. Relevant equations

3. The attempt at a solution

2. May 18, 2017

### haruspex

That is rather garbled. Please clarify.

With regard to the question, I do not understand how you are supposed to know exactly where B is.

3. May 19, 2017

### Lamar Ngolo

I was meant to put between odd numbers of nodes is the phase difference pi radians?

4. May 19, 2017

### haruspex

Ok.
In this question, O, A and C are antinodes, but the same method applies.
Counting from O, how many antinodes away is A? Is that an even or odd number?
How about from O to C?

5. May 19, 2017

### Lamar Ngolo

Would it not just be Pi rad for A and B and 0 for C?

6. May 19, 2017

### haruspex

π For A and 0 for C, but B is not at a node or antinode. As I wrote, from the information given, I don't know how you are supposed to know exactly where B is.