Tuesday, February 1Tuesday, February 1stst, 2011, 2011

Tasks

Take out Electromagnetic WS

Learning Targets

Explain the difference between reflection and refraction

Homework

Study for Quiz tomorrow!

Complete light and color study guide

Q.O.D.

What type of materials reflect light?

Reflection & Refraction

Ch. 20

Reflection

• Reflection:

– Wave strikes an object and bounces off

– Example:• Mirror

Reflection

• Law of Reflection

– States that the angle of incidence is equal to the angle of reflection

– Angle in = angle out

Reflection

MIRROR

Normal

Incidence wave

Reflected wave

i = angle of incidence

r = angle of reflection

Reflection

• Smooth surfaces reflect light in 1 direction.

• Rough surfaces scatter light in many directions.

Refraction

• Refraction:– Bending of waves caused

by a change in their speed when they move from 1 medium to another.

– Examples: prisms, water, lenses

– Light travels faster in less dense media

Refraction

#1 Air

Water

Normal

Refraction

• When light slows down (goes from gas to liquid to solid):

– Light is refracted (bent) toward the normal (#1)

Refraction

#2Water

Normal

Air

Refraction

• When light speeds up (goes from solid to liquid to gas):

– Light is refracted (bent) away from normal (#2)

Visible Light Spectrum

• Red (longest wavelength)– Less refracted

less bending

• Violet (shortest wavelength)– More refracted

more bending