### Water waves reflecting off boundaries.

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Teachable Topics:

• Reflection
• Interference
• Traveling Waves

Theory:

Reflection is what happens when incident waves meet a new medium, but are reflected back into the first medium. Reflection is not only visible in water waves, but sound and light waves too.

When reflection occurs, the angle between the incoming (incident) wave and the normal is the same as the angle between the reflected wave and the normal. The normal is an imaginary line perpendicular to the medium the waves are reflecting off of, and is located at the point the incident waves strike the second medium. As such, the equation for reflection is:

θi = θr

where θis the angle of incidence and θr is the angle of reflection.

Apparatus:

• Ripple Tank

Procedure:

• Set up the ripple tank and turn it on. Place a boundary in the tank and observe the interference pattern.
• Try placing the boundary at different angles to see what kind of patterns you can get. Also try using differently shape boundaries.