Optics Refraction and Reflection

Law of Refraction How it works:

Law of Refraction n 1 sin Θ 1 = n 2 sin Θ 2 n = index of refraction = c/v Vacuum: n = 1 Air: n ~ (sunset) Water ~ 1.3 (aquarium) Glass ~ 1.5 (optics) Highest? … … diamond

Atmospheric Optics: Rings

Source of 22 O Angle

How it works Blue refracted more than red – this is called dispersion

Rainbows

Optics of Rainbows Total internal reflection

Images

Extended Object

Diverging Lenses

Applications to Eyewear How it works

Problems with lenses…

The fix

Another problem

Other problems with lenses Glass must be pure and clear Glass sags—lenses only supported at edge Solution ….

Reflective Optics First-surface mirror!

Images

Extended Objects

This divergence is used to extend the focus in reflecting telescopes… Diverging Mirrors

Magnification = F O /F E Example: 50/0.5 = 100x Magnification is the least important characteristic of a ‘scope! The most important is the diameter of the objective! Refracting (lens based) Telescopes