Reflection and Mirrors

Chapter 23 Lesson 2 Notes

Law of Reflection

• The law of reflection says that the angle of incidence is equal to the angle of reflection.

Angle of Reflection

Angle of Incidence

Incident R

ay

Reflected Ray

Normal

Flashlight

Diffuse Reflection

• The uneven reflection of light waves from a rough surface is called diffuse reflection.

Regular Reflection

• Regular reflection results from a smooth surface such as a mirror.

Scattering

• Scattering – Light waves traveling in one direction are made to travel in many directions.

– Example – dust in a beam of light

Plane Mirror

• Plane mirror – reflects an actual size image that seems to be behind the mirror due to the way the brain interprets light.

*Looks like a photograph

*Opposite image

*Image seems to come from behind the mirror

Plane Mirror

Concave Mirror

• Concave mirrors cause light rays to converge.

– In a concave mirror, light waves parallel to the optical axis reflect and pass through the focal point.

– Focal length – distance along the optical axis from the center of the mirror to the focal point.

Concave Mirror

– The image formed by a concave mirror depends on the position of an object relative to the focal point.

– Flashlights and headlights form a beam of light when a light source is placed at the mirror’s focal point.

Concave Mirror

Focal Point

Optical Axis

1. If object is farther from the mirror than the focal point Upside Down.

2. If object is closer to the mirror than one focal length Upright and gets smaller as you move closer to the mirror.

If an object is placed outside the focal point its image is real, upside-

down, and enlarged.

If an object is located within the focal length, its

image is virtual, upright, and enlarged

Concave Mirror

Examples of Concave Mirrors

Convex Mirrors

• Convex mirrors cause light rays to diverge.

– The image formed by a convex mirror is upright and smaller than the actual object.

– Convex mirrors are used for security in stores and on the outside rearview mirror of vehicles.

Convex

When you hear “convex” – picture a pregnant belly

The image in a convex mirror is ALWAYS

virtual, upright, and small

Convex Mirrors

Optical Axis

1. Image seems to be behind the mirror.

2. Image is upright and smaller.

Convex Mirrors

Examples of Convex Mirrors