Huygens Principle

1. HUYGENS PRINCIPLE

2. WHAT IS IT?
Method of analysis applied to problems using wave propagation
Source: Wikipedia pictures

3. PROPOSAL
1678 from Christiaan Huygens
Every point on a wave-front may be considered a source of secondary spherical
wavelets which spread out in the forward direction at the speed of light. The new
wave-front is the tangential surface to all of these secondary wavelets.
(farside.ph.utexas.edu)
Assumed that secondary waves only travelled in “forward” direction
Provided a qualitative explanation of linear and spherical wave propagation
Derived the laws of reflection and refraction
Couldn’t explain the diffraction aspect

4. HYGUYENS PRINCIPLE
Steps in how to apply:
1. Start anywhere of the original wave-
front.
2. Draw a circle with any radius.
3. Repeat for the rest of the points you
choose with the same radius.
4. You now have your new wave-front

5. NOT ONLY LIGHT WAVES
Interference works for all different waves
Can show how a ray travels from one
medium to another
The figure shows how refractions works
Ray will refract since it’s a different
medium

6. REFLECTION
Can see how the rays would be reflected
Same pattern would happen
Rays are reflected downwards because the
angle of the mirror is pointed downwards
Originally moving from left to right

7. SOURCES
http://farside.ph.utexas.edu/teaching/302l/lectures/node150.html
http://physics.about.com/od/mathematicsofwaves/a/huygensprincip
l.htm
https://www.boundless.com/physics/textbooks/boundless-physics-
textbook/wave-optics-26/diffraction-175/huygens-principle-636-
5593/
http://www.mathpages.com/home/kmath242/kmath242.htm