PHY C15: Superposition

New chapter!

  • Principle of Superposition
  • Interference
  • Path difference

Here we go:

What is superposition?
Multiple waves passing through the same point.

What is interference?
The phenomena that occurs when waves superpose – it is described through the principle of superposition.

What is the principle of superposition?
“When multiple waves pass through a point, the resultant displacement at that point is equal to the sum of the displacements of individual waves at that point.”

Example: 2 Individual Waves Interfering

Image result for superposition wave gif
From OPhysics: check out their interactive page!

There are 2 Types of Interference:

Constructive Interference
Image result for constructive interference gif
Crest + Crest OR Trough + Trough Displacements ADD UP to have a larger value Maximum displacement
Destructive Interference
Image result for destructive interference gif
Crest + Trough Displacements CANCEL OUT to have smaller value For identical waves, 0 displacement

However, interference can happen between ANY waves as long as they are in the same medium.

Waves with different frequencies, amplitudes, or phase can interfere – the principle of superposition will be true: the resultant displacement = sum of individual displacements.

A Classic Example: 2 Wave Sources

Image result for double slit interference gif

When two point sources emit waves radially, the waves can interfere & form alternating patterns. This is due to path difference.

What is a path difference?
The difference in length travelled by 2 waves across a path from a SOURCE to a POINT where they superpose.

Image result for path difference
From Quizlet
When path difference is a WHOLE multiple of λ:Maximum constructive interference
When path difference is an ODD multiple of λ/2:Maximum destructive interference (antiphase)
Otherwise:A combination

Now that you know the basics of interference & superposition, we can branch off into a few other sections:

⇐ Previous in Physics: Electromagnetic Spectrum
⇒ Next in Physics: Stationary Waves

One thought on “PHY C15: Superposition

  1. Pingback: 15. Superposition – ProDuckThieves

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