14.2 Flat Mirrorspp. 526 - 529

Mr. Richter

Agenda

Warm-Up Review HW Introduction to Reflection Notes:

Reflection Law of Reflection Flat Mirror Images

Objectives: We Will Be Able To… Distinguish between specular and diffuse reflection of

light. Apply the law of reflection for flat mirrors. Describe the nature of images formed by flat mirrors.

Warm-Up:

If the pencil in this picture is 2.5 inches away from the mirror, how far does the image of the pencil appear to be from the pencil itself?

Reflection

Reflection

Light traveling in a uniform substance (air, water, etc.) will travel in a straight line…

Until it encounters a different substance (boundary).

When it hits the boundary, part of the light is absorbed, and part is sent off in another direction.

Reflection

This is called reflection: the turning back of an electromagnetic wave at the surface of a substance.

A good mirror can reflect 90% of the incident (incoming) light.

Texture Surface affects Reflection If a surface is smooth, all of the reflected light heads in

the same direction. This is called specular reflection.

If a surface is rough, the reflected light heads in many different directions. This is called diffuse reflection.

The Law of Reflection:

If a surface is relatively smooth, the angle at which light strikes the surface is equal to the angle at which it leaves the surface.

In other words, the angle of incidence is equal to the angle of reflection.

θ=θ’

Mirror Images

Mirror Images

When light from an object strikes a mirror, an image is formed.

This is a virtual image, meaning it cannot be projected onto another surface.

It only exists “inside” the mirror.

Mirror Images

The distance of the object from the mirror is equal to the distance of the image from the mirror. Object distance = image

distance.

The image appears to be the same size as the object.

Mirror Images

Images formed by a flat mirror appear to have a left-to-right reversal.

Leonardo da Vinci famously wrote with a mirror to make it harder for people to copy his notes.

Wrap-Up: Did we meet our objectives?

Distinguish between specular and diffuse reflection of light.

Apply the law of reflection for flat mirrors. Describe the nature of images formed by flat mirrors.

Homework

p. 529 #1-6