18.3 Behavior of Light• Light and Materials – How light behaves when

it hits a surface depends on the material it is made of

• Materials can beTransparent - A material that transmits

(allows through) light unaffectedTranslucent - A material that transmits light but scatters it into different directions Opaque – A material that does not transmit any light. Light is either absorbed, reflected, or both.

The jelly fish is Transulcent

These bananas are opaque

This cell phone is transparent

18.3 Behavior of Light

Interactions of Light – When light strikes a new medium there are three possible outcomes

I ReflectionII AbsorptionIII Transmission

Reflection - Light bouncing off an object to form an image. We depend on reflection to see.

Regular reflection – light bounces off an object in the same direction to from a reflected imageDiffuse reflection – light bounces off an object in different directions no reflected image formed

Regular and Diffuse Reflection

Images are formed by Regular reflection

NOTE: Absorption of light produces the colors we see. Only the color reflected reaches our eyes

When light is transmitted there are three possible outcomes

I Refraction – Bending of light as it enters a new medium (Chapter 17)II Polarization – Occurs when light waves vibrate in only one plane.III Scattering – Light waves are bent as it diffracts around tiny particles in the

atmosphere

I. Refraction of light causes this affect

Remember the light changes speed as it enters the new medium causing it to change direction

A mirage is caused by diffraction of light through different layers of heated air

http://www.youtube.com/watch?v=_M0FcpQWh5E

II. Most light is unpolarized and vibrates in all directions a polarizing filter will allow only light vibrating in a single plane to pass.

Reflected light (glare) is often polarized and is blocked by polarized glasses

The sky looks blue because of scattering and sunsets Look red.

This sunset is caused by scattering. Only the longer wave lengths get through.