Phase difference between the two waves

[Sloan650]

1) Two sine waves have equal peak to peak amplitudes 89 but are out of phase by 180 degrees. What is the peak to peak amplitude of the resultant wave.

2)Two sine waves have equal peak to peak amplitudes 81 but are out of phase by 90 degrees. What is the peak to peak amplitude of the resultant wave.

3) Light from a single source goes from O to X via two paths: directly OX, path length 10.29600 mm and indirectly OYX, path length 10.29765 mm. The wavelength is 660 nm. What is the phase difference between the two waves when they meet at X.

 

[lewando]

Hello Sloan650, welcome to PF! Maybe you didn't get a chance to read the forum rules. The thing you need to do is show what work you have done. If you have done very little, the odds of getting any help are low. If you show a sincere effort, your stock will rise. Give the problems a try!