# NCERT Class 11 Physics Solutions: Chapter 15 – Waves-Part 7

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**Question 15.12:**

For the wave on a string described in Exercise , do all the points on the string oscillate with the same,

Frequency,

Phase,

Amplitude?

Explain your answers. What is the amplitude of a point away from one end?

**Answer:**

**For** **;**

**Frequency,:**

Yes, except at the nodes

**Explanation:**

All the points on the string oscillate with the same frequency, except at the nodes which have zero frequency

**Phase:**

Yes, except at the nodes

**Explanation:**

All the points in any vibrating loop have the same phase, except at the nodes.

**Amplitude:**

No

**Explanation:**

All the points in any vibrating loop have different amplitudes of vibration.

**For****;**

The given equation is:

For

AmplitudeDisplacement

**Question 15.13:**

Given below are some functions of to represent the displacement (transverse or longitudinal) of an elastic wave. State which of these represent

A traveling wave,

A stationary wave or

none at all:

**Answer:**

**Explanation:**

The given equation represents a stationary wave because the harmonic terms appear separately in the equation.

**Explanation:**

The given equation does not contain any harmonic term. Therefore, it does not represent travelling wave or a stationary wave.

**Explanation:**

The given equation represents a travelling wave as the harmonic terms the combination of

**Explanation:**

The given equation represents a stationary wave because the harmonic terms appear separately in the equation. This equation actually represents the superposition of two stationary waves.