Phase and Path Difference
There is a very simple relationship between the phase and path difference.
A whole wavelength corresponds to one whole oscillation, a path difference ofThis is turn corresponds to a phase difference ofor 360 °. Confusion arises because many waves are sinusoidal so the displacement from equilibrium is given bywhereso whenincreases byincreases by
The angle however may also be measured in degrees so a phase difference of %pi means the same as a phase difference of 180°, and both of these are equivalent to a path difference of
The following table shows equivalent path and phase difference for different phase/path differences.
Path difference | Phase Difference in Degrees | Phase Difference in Radians |
0 | 0° | 0 |
45° | ||
90° | ||
135° | ||
180° | ||
225° | ||
270° | ||
315° | ||
360° |