Wave Propagation and Huygens’ PrinciplePhysics 101 LO7

Spherical Wave

When you drop a rock into a lake you see waves moving out in a circle on the surface of the water away from the point at which the rock hit. What you might not know is that there is actually a whole sphere of waves moving away from that point but you can only see the water waves due to the properties of that medium.

Huygens’ Principle

Huygens’ principal is a theory developed by Christian Huygens which allows the propagation of a wave to be described by considering any point on a wave front to be a source of spherical waves.

Procedure for applying Huygens’ principle:1- Select a set of equally spaced points on a wave front.

2- Draw a set of circles, all of the same radius, each centered at a different point.

3- Construct the resulting wave front by drawing tangents the the circles.

Huygens’ Principle

Huygens’ Principle : Each wave front is the envelope of the wavelets. Each point on a wavefront acts as an independent source to generate wavelets for the next wavefront. AB and CD are 2 different wavefronts(left diagram).

A Spherical wave that can actually be seen!

This is a video of a volcanic eruption in which the spherical wave created from the eruption can be seen moving clouds.

A good example to show a spherical wave but also very amazing to see!

https://www.youtube.com/watch?v=BUREX8aFbMs