What happens when two wave pulses collide?

Interference – Two waves “collide,” but pass through each other undamaged – Superposition Principle: when waves interfere with each other, the resulting wave is the sum of their amplitude at each point.

Destructive Interference

Constructive Interference

crests aligned with crests waves are “out of phase”

Destructive Interference crests aligned with troughs waves are “out of phase”

Interference – Add the amplitudes of the waves Above axis is positive, below is negative – The result is the superposition of the waves – Constructive  wave gets bigger – Destructive  wave gets smaller

What if we send a bunch of pulses down the spring and let them reflect back? How will they interfere with one another?

Standing waves Animation

Parts of a Wave 246 x(m) 3 -3 y(m) Crest/antinode Trough/antinode node

Wave Parameters x(m) y(m) amplitude wavelength

You can make a standing wave on a spring. – Figure out how to make different standing waves. – What would a graph of wavelength vs. # of antinodes look like? – Collect the data to make this graph. Wavelength # of antinodes