# Wave Exercises

## 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.