## Propagation Speed

**1.** The graph below represents a wave that propagates at a speed of 300m / s.

Determine:

a) the amplitude of the wave;

*The amplitude of the wave is given by the distance from the origin to the crest of the wave, ie:*

b) the wavelength;

*The wavelength is given by the distance between two ridges or between 3 nodes, ie:*

*As the figure shows the measurement of three "half wavelengths", we can calculate it:*

c) the frequency;

*Knowing the propagation speed and wavelength, we can calculate the frequency through the equation:*

*Substituting the values in the equation:*

d) the period.

*Since the period is equal to the inverse of frequency:*

## Wave refraction

**1. **A vibrating needle produces waves with a propagation velocity of 160m / s and a wavelength of 1mm, arriving at a depth difference of 45 ° and being refracted. After changing depths the refracted angle becomes 30 °. What is the new wave progression speed?

And the length of the refracted waves?

*Using Snell's Law*:

*Using the relation with propagation velocities, we arrive at the equation:*

*The speed of the refracted wave will be 113.1m / s.*

*To calculate the refracted wavelength, we use Snell's Law, using the relationship with wavelengths:*

*The refracted wavelength will be 0.7mm.*

*Note that the result appears in millimeters because units were not converted to SI at the beginning of the resolution.*