WARM-UP ON YOUR HANDOUT PAGE, PLEASE DO THE FOLLOWING: Define the word LENS in your own words. Then list at least 3 examples of lenses in everyday life.

WARM-UPWARM-UPON YOUR HANDOUT PAGE, PLEASE DO THE FOLLOWING:ON YOUR HANDOUT PAGE, PLEASE DO THE FOLLOWING:

Define the word LENS in your own words.

Then list at least 3 examples of lenses in everyday life.

Title: Light and LensesTitle: Light and Lenses

Challenge Question:Challenge Question:

What is a lens, and how does it change the path of light?

Take time now to write down your Initial Ideas!

• The sun emits energy that makes up the electromagnetic spectrum.

• Visible light makes up only a small part of this broad spectrum.

Evidence/Evidence/Data:Data:

While otherparts of the electromagneticspectrumcan be detected,the human eye canonly detect visiblelight.

Light travels in straight lines away from its source ...

Laser

until it is re-directed by an object….

Light travels in straight lines Light travels in straight lines away from its source ...away from its source ...

Laser

Until it is re-directed by an object…..this is called RELFECTION

We see things because they reflect light into our eyes:

Homework

Reflection of Light:Reflection of Light:Reflection from a mirror:

Incident ray

Normal

Reflected ray

Angle of incidence

Angle of reflection

Mirror

The Law of ReflectionThe Law of Reflection

Angle of incidence = Angle of Angle of incidence = Angle of reflectionreflection

In other words, light gets reflected from a surface at ____ _____ angle it hits it.

The same !

!!

• White light is not a single color. It is made up of a mixture of the seven colors of the rainbow.

• We can demonstrate this by splitting white light with a prism.

This is how rainbows are formed. Sunlight is “split up” by raindrops.

Adding colorsAdding colorsWhite light can be split up to make separate

colors. These colors can be added together again.

The primary colors of light are red, blue and green:Adding blue and

red makes magenta (purple)

Adding blue and green makes cyan

(light blue)

Adding all three makes white again

Adding red and green makes yellow

Seeing colorSeeing colorThe color an object appears depends on the

colors of light it reflects.

For example, a red book only reflects red light:

White

light

Only red light is

reflected

A white hat would reflect all seven colors:

A pair of purple trousers would reflect purple light (and red and blue, as purple is made up of red and

blue):

Purple light

White

light

Refraction of Light:Refraction of Light:

Light can also be refracted. Refraction is the bending of light as it passes from one transparent material (such as air) into another transparent material (such as water).

The ruler looks bent because the light is refracted as it passes from the air into the water.

A lens is a curved transparent object that refracts light.

Light rays

Lens

There are different types of lenses.

A convex (or converging) lens is thicker in the middle than at its edges. It bends light toward its center.

A concave (or diverging) lens is thinner in the middle than at its edges. It bends light away from its center.

Convex Lens

Concave Lens

Lenses are used in many different applications, including….

Convex

lenses

Combination of convex & concave lenses

Analysis Questions:Analysis Questions:1. What is the difference between the

reflection of light and the refraction of light?

2. What are the different types of lenses, and where can they be found in everyday life?

3. When light is refracted it is bent as it passes from one transparent material to another. Why does the light bend?