MIRANDA CALANDROSPRING 2011

Waves Wrap-Up

Warm up

Go to the online textbook and open chapter 14

Complete problems 15-19 on p. 386

Behaviors of Waves

Interference – two waves occupy the same space at the same time Constructive – combine to produce a larger wave Destructive – waves subtract from each other or

cancel each other out completely

Reflection – a wave strikes an object and bounces off

Types of Reflection

Total Internal Reflection

The critical angle of incidence has been exceeded; a wave (light) strikes an object and is continually reflected throughout a material.

Ex.: Fiber optic cable

Critical Angle

Θc = n2/n1

For air, sinθc = 1/n1

Example 1

The index of refraction for water is 1.33. Above the water is air. What is the critical angle of incidence for light starting inside the water and passing into the air above it?

Example 2

A diamond with an index of refraction of 2.42 is surrounded by air. If a ray of light originating inside the diamond strikes the surface of a facet at an angle of 27 degrees from the normal, will the ray be refracted or will it experience total internal reflection?

Diffraction

Diffraction – a wave passes through an opening and bends and changes direction

Refraction - waves bend and change directions and speed when they travel from one medium into another

Law of Refraction (Snell’s Law)

n1 sinθ1 = n2sinθ2

n=index of refraction (different for every medium)

n(air) = 1.00

Example 1

A ray of light passes through air and strikes a piece of glass at an angle of 45 degrees from the normal. If the index of refraction of glass is 1.60, what will be the angle of refraction?

Example 2

Light passes through air and strikes the surface of a piece of glass at an angle of 58 degrees from the normal. The angle of refraction is 33 degrees measured from the normal. Calculate the index of refraction for the glass.

Polarization of Light

When light passes through two polarized filters perpendicular to each other, light is completely blocked.

Doppler Effect

Change in frequency perceived by an observer moving relative to a wave source.