# NCERT Class 11 Physics Solutions: Chapter 15 – Waves-Part 5 (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Question 15.9**:

For the wave described in Exercise, plot the displacement graphs for What are the shapes of these graphs? In which aspects does the oscillatory motion in travelling wave differ from one point to another: amplitude, frequency or phase?

**Answer**:

All the waves have different phases.

The given transverse harmonic wave is:

For , the equation reduces to:

Also,

Now, plotting graphs using the different values of , as listed in the given table.

For the phases of the three waves will get changed. This is because amplitude and frequency are invariant for any change in The plots of the three waves are shown in the given figure:

**Question 15.10**:

For the travelling harmonic wave

Where are in . Calculate the phase difference between oscillatory motion of two points separated by a distance of

**Answer**:

Equation for a travelling harmonic wave is given as:

Where,

Propagation constant,

Amplitude,

Angular frequency,

Phase difference is given by the relation:

For

:

For

For

For