Wave Actions

Wave Shapes

• Wave front– shape of a wave is determined by the shape of

wave fronts1. A plane wave look like straight lines

2. A circular wave’s crests are in circles

Wave Interactions

• Waves lose energy due to friction• Damping – Amplitude of the wave decreases

over time

• As a wave travels, it approaches boundaries of different mediums– Reacts depending on type of boundary

Types of Wave Interactions

1. Absorption - when a wave’s energy dies out in a soft material (damping)– Ex: Yelling into a pillow – the soft pillow absorbs

the sound

2. Reflection - when a wave hits a hard boundary and bounces off– Ex: an echo – when you yell, the waves bounce off

a wall in the distance and travel back to you

3. Diffraction - a wave drags around a corner, causes part of the wave to turn– Ex: talking to someone around a corner

• Diffraction also happens when plane waves go through a small opening – they turn into circular waves

• Ex: being able to hear someone through a door that is cracked open

4. Refraction - when a wave bends as it enters a new medium • it speeds up or slows down depending on

the medium– Ex: Try catching a fish by reaching for what you

see.

Phase

• In-phase– 2 waves are in same part

of their cycles

• Out-of-phase– 2 waves at different

points of their cycles

Interference:

• Interference happens when two or more waves come together1. Constructive Interference

energy of two waves in-phase add together

2. Destructive Interference energy of two waves out-of-phase subtract from each other, causing cancellation

Works Cited

• Hsu Ph.D., Tom. Foundations of Physical Science. 1st ed. Peabody: Cambridge Physics Outlet, 2002. 195-202. Print.

• Murray, Stephen. "Worksheets." Mr. Murray’s Science Website: IPC Worksheets. N.p., 2009. Web. 18 May 2012. http://www.cstephenmurray.com/Acrobatfiles/IPC/ch11to13/chap12no2.pdf .