Interference Diffraction Chapter 26 Definitions Monochromatic Polychromatic Light

Interference & Diffraction Chapter 26

Definitions Monochromatic Polychromatic Light Waves of one wavelength, or A single color (same thing) Many wavelengths White Light A mixture of all colors

Again

Color Light OOO. . It’s Red!

Remember Huygens‘ Principle?

A long distance from the center you have a plane wave approximation.

Adding Waves

In Phase This is called CONSTRUCTIVE Interference

Destructive Interference

Interference and Diffraction Everything is based upon how separate waves interact with each other, usually a long distance from the source. Huygen’s principle applies. These waves add Constructively … they produce a bright intensity Destructively … they produce a dark band where little light appears.

Young’s Experiment (Double Slit Expt. ) Produces a small region Light which mimics Source a coherent light source The light from S 1 & S 2 are in-phase The rays add up to produce bright and dark bands where rays from S 1 and S 2 are in or out of phase when they get to the screen

Staying Young r 1 and r 2 are PARALLEL!! (R>>d)

Overview of Young’s Thingy (What is l? )

Ye olde oil slick

An inconvenient fact: Phase shifts on reflection: No shift of l/2 Hmmmm

NO phase change at (b) or (d) W H Y ?

Newton’s Rings

Testing a Lens

Anti-reflective coatings