Q.Explain what is meant by phase of a wave.

[!TLDR] The phase of a wave is the instantaneous state of oscillation of a particle -- fixed by its displacement, the direction of its velocity, and which oscillation cycle it is in. [!ANSWER …

The phase of a particle in a wave is its complete instantaneous state of oscillation. To specify it fully requires knowing three things simultaneously: (a) the particle's current displacement, (b) the direction its velocity is currently pointing, and (c) which oscillation (its 1st, 2nd, 3rd, ... cycle since the disturbance first reached it) it is currently undergoing. Because a sinusoidal wave's displacement varies as a sine function of both position and time, phase is most conveniently expressed as an ANGLE -- the particle at the very leading edge of the disturbance is assigned phase 0°, and every quarter-wavelength further behind it (equivalently, every quarter-period later in its own oscillation) adds another 90° ($\pi^c/2$) to the phase angle, with a full wavelength/period of separation corresponding to a full $2\pi^c$ (360°) of phase. Two particles are 'in phase' when both the …

Give the three-part definition of phase (displacement + velocity direction + oscillation number) and connect it to th …

Defining phase using ONLY the particle's displacement, omitting the velocity-direction requirement -- two particles can have the identical displacement at a given instant while m …