# Phase Difference of Wave and Reflected Wave

lordy2010

## Homework Statement

A source is transmitting a sound wave of frequency 115 Hz. A receiver detects the direct sound wave and the sound reflected from a small section of wall. Speed of sound is 345 m/s.

It also gives a diagram of sound waves leaving a source, one hitting the wall, reflecting, and travelling a total of 26 metres to reach the receiver and the other going 24 metres directly to the receiver.

What is the phase difference between the direct and reflected wave?

## Homework Equations

$$\lambda = \frac{v}{f}$$

$$\Delta\phi = 2\pi\frac{d}{\lambda}$$

## The Attempt at a Solution

I thought the phase difference was just kd, where k = 2pi / wavelength. So I went and figured out d which is 26 - 24 = 2, and wavelength, which turned out to be 3 m.