Reflection of

Light 13.2Karla Mendez and Shelby Bowen

Introduction

• In this lesson we are going to talk about

what reflection is and the difference

between specular and diffuse reflection of

light. We will also be applying the law of

reflection for flat mirrors and explain and

describe images formed by flat mirrors.

Key Words

• Reflection

• Angle of incidence

• Angle of reflection

• Virtual image

• Specular reflection is defined as light

reflected from a smooth surface at a

defined angle.

• This is an example of specular reflection.

Specular Reflection

Diffuse Reflection

• Diffuse reflection is reflection off of rough

surfaces such as clothing, paper, and the

asphalt roadway.

• Diffuse reflection originates from a

combination of internal scattering of light.

• Diffuse reflection allows us to see most

things around us.

o Example: Light is diffusely reflected from a paper in

many directions.

Diffuse Reflection

• You can see that the the reflection of the

light hitting the rough surface causes

it to scatter in

many different

directions.

What is the Law

of Reflection (flat mirrors)?

• Reflection is when a ray of light strikes a

plane mirror, the light ray reflects off the

mirror.

• Flat mirrors are the simplest form of a

mirrors

• Reflection is a change in direction of the

light ray.

• The law states that the angle of incidence

is equal to the angle of reflection.

Key words on the

Law of Reflection

• Angle of incidence

• Angle of reflection

• Incident ray

• Reflection ray

• “Normal”

What is the angle

of incidence?

• Angle of incidence is the angle between a

beam incident on a surface and the

normal.

• Line perpendicular to the surface at the

point of incidence.

●

● The red line

represents the

incident ray

(sunlight)

● The black line

represents the

normal

● The angle

between the two

is called the

angle of

incidence

What is the angle

of reflection?

• The angle between a reflected ray and the

normal, drawn at the point of incidence to a

reflecting surface.

• Light reflects off a mirror at the same angle

as it did when it (incident ray) hit the mirror.

• A mirror can only reflect 90% of incident

light.

The distance between

the normal (dotted line)

and the reflected ray

(red line) is the angle of

reflection.

Images formed by flat

mirrors

-Whats an image?

❖A real image of an object produces the

same pattern of light as the object does

somewhere in space.

❖A virtual image is the apparent position

from which a pattern of light reaches our

detector, if we make the assumption that it

has traveled from its source to the detector

along a straight-line path.

Real image

Virtual

The reason

why the

virtual image

looks lighter

is because

only 90% of

the original

image is

being

reflected by

the mirror.

What’s in the

mirror?

• When you look in the mirror you are looking

at a reversed you!

• The image of your left is now on the right

and your right is on the left. o Example: When you are brushing your teeth and you

have a shirt on the says Hollister, in the mirror it will

be backwards because a mirror reverses the virtual

image (image in the mirror) from the original (real

image).

The baby’s reflection is

reversed. You can see that the

baby’s right side of its body is

reflected on the left and the left

is on the right

Images Formed by flat

mirrors continued..

• Mirrors can produce real and virtual

images by reflection.

• A flat mirror only produces virtual images.

• The Law of Specular Reflection states that

light reflecting from a plane mirror forms an

angle to the NORMAL equal to the angle

between the normal and the incident light.

Summary

● Specular reflection is defined as light

reflected from a smooth surface at a

defined angle.

● Diffuse reflection is reflection off of rough

surfaces

○ clothing, paper, asphalt roadway

○ scattering of light

○ allows us to see most things

Summary

(Continued)

• Reflection is when a ray of light strikes a

plane mirroro flat mirrors are the simplest form of mirrors

o reflection is a change of reflection in a light ray

• The law of Reflection states that the angle

of incidence is equal to the angle of

reflection

Summary

(Continued)

• Angle of incidence is the angle between a

beam incident on a surface and the

normal.

• The angle between a reflected ray and the

normal, drawn at the point of incidence to a

reflecting surface.

Summary

(Continued)

• A real image of an object produces the

same pattern of light as the object does

somewhere in space.o Example: You

• A virtual image is the apparent position

from which a pattern of light reaches our

detectoro Example: Your reflection in the mirror

Summary

(Continued)

• Mirrors can produce real and virtual

images by reflection.

• A flat mirror only produces virtual images.o Example: The mirror in your bathroom

Questions?

Bibliography All Things Reflected. (n.d.). Optics For Kids. Retrieved October 25, 2013,

from http://www.optics4kids.org/home/teachersparents/articles/the-

reflection-of-light/

Molecular Expressions Microscopy Primer: Light and Color - Reflection of

Light: Interactive Java Tutorial. (1998, June 21). Molecular Expressions

Microscopy Primer: Light and Color - Reflection of Light: Interactive Java

Tutorial. Retrieved October 25, 2013, from

http://micro.magnet.fsu.edu/primer/java/reflection

Reflection of light. (2012, April 18). Science Learning Hub RSS. Retrieved

October 25, 2013, from http://www.sciencelearn.org.nz/Contexts/Light-and-

Sight/Science-Ideas-and-Concepts/Reflection-of-light