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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?
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