Properties of Light

Mirrors and Lenses

Unit 12

Electromagnetic Waves

Travel through a vacuum.•No medium

•Radiation

Travel at the speed of light.•3 X 108 m/s

Visible Light

Red

Orange

Yellow

Green

Blue

Indigo

VioletROYGBIV

Law

of Reflection

Law of Reflection

NormalIncidentRay

ReflectedRay

θi θr

Law of Reflection

θi – angle of Incidenceθr – angle of Reflection

θi = θr

Plane Mirror

Object Image

dodi

VirtualUpright

do = di

Virtual Image

Images which are formed in locations where light does not actually reach.

Appears to be inside the mirror or lens.

Regular vs. Diffuse Reflection

Concave – Convex Mirrors

Concave Mirrors

Convex Mirror

Concave Mirrors

2 C F

F – Focal Point of the mirror.

C – Center of Curvature.

Concave Mirrors

C F

Concave Mirrors

C F

RealInverted

Concave Mirrors

C Ff

dodi

Concave Mirrors

C F

Concave Mirrors

C FNo Image

Concave Mirrors

C F

UprightVirtual

Convex Mirrors

CF

UprightVirtual

C F

Scale: 1 box = 2.5cm

Homework 18-1

Practice problems:1-5, 6-8

Pages: 425,427Review: 18-1 Page: 428

Due: 5/2/03

Refraction

Light Light and and

ColorColor

Transparent

Material that passes or

transmits light.

Opaque

Material that adsorbs light. No

light will pass through.

Translucent

Materials that light will shine through, but you cannot see clearly through it.

Retina

How we see colors?

Primary Colors (light)

Red

Green

Blue

White

Blue

Red Green

Color Blindness

The color receptors in the eyes (cones) do not function

correctly.

   Inherited Condition

   8% of Men   ½% of women

Ability to distinguish between colors.

Primarily red and green.Green cones are deficient.

25

29

45

56

6

8

Types of Lenses

Convex Lens – A lens that is thicker in the center than at the edges.

Types of Lenses

Concave Lens – A lens that is thinner in the center than at the edges.

Nearsighted

Farsighted

Focal Point For a convex lens the point where parallel rays converge.

Focal Point

Focal Point

For a concave lens the point where parallel rays diverge.

Focal Point

Convex Lens Ray Diagram

F2F

2FF

Image: Real Inverted

1.Parallel Rays go through the focal point. 2.Rays going through the middle go straight. 3.Rays going through the focal point come out parallel.

F F

Image: VirtualUpright

Concaved LensRay Diagram

1.Parallel Rays come from the focal point. 2.Rays going through the middle go straight. 3.Rays going through the focal point come out parallel.

Telescope

Telescope

Microscope