​Reflection of waves

​Watch the video and notice the direction that the wave fronts are reflected by the straight solid boundary.

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The reflection for a light ray is similar to that of a wave.

The angle of incidence is measured from the light ray to the normal line.

The angle of reflection is also measured the same.

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Notice how the angle of incidence and the angle of refraction is labelled.

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​It is according to the how the light ray travels.

​Refraction of waves

​To answer the next question, observe the how the wave fronts change direction, wavelength and speed as it passes through a medium of higher density.

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​Note, the distance between the wave fronts is the wavelength of the wave.