K-12 Science, CCSD, 2006 Light Photos, sounds, and clipart were inserted from Microsoft’s Office...

K-12 Science, CCSD, 2006

Light

Photos, sounds, and clipart were inserted from Microsoft’s Office products unless noted.


Waves

Remember? A wave is energy being moved from one place to another.


Light Waves

• Light is another kind of energy that moves in waves.

• Write down 6 words to describe light.


Light Waves

• Light is another kind of energy that moves in waves.

• Light waves do not need a medium. They can travel through nothing!


Light Waves

• Explain why we get light from the sun but not any sounds.


Light Waves

• Light waves can be reflected.

• Light waves can be refracted (bent).

• Light waves can be absorbed.


Light Wavelength

• Just like sound, light has different wavelengths.

• Review the parts of a wave:


Parts of a Wave

A = Crest

B = Trough

D = one full wave

= one wavelength

= one period

C = AmplitudeCA

B

D


Light Wavelengths

• Light has different wavelengths.Red light has a large wavelength.

Blue light has a shorter wavelength.


Light Wavelengths

Red light has a large wavelength.


• Would it take longer for a red light wave or a blue light wave to go past a point?


FrequencyRed light has a large wavelength.


• The shorter, blue wavelengths would go past quicker.


Frequency

Large wavelength = low frequency

Medium wavelength = medium frequency

Small wavelength = high frequency


Frequency

• Don’t confuse the frequency with the speed of a wave.

• Here’s an analogy:


FrequencyIf you were looking down on a freeway . . .

And all of the vehicles were going exactly 60 miles per hour (the same speed). . .


Frequency Small cars going 60 miles per hour


Frequency Bigger cars going 60 miles per hour


Frequency Really big vehicles going 60 miles per hour


Frequency Speed = 60 miles per hour

Small cars = high frequency (6)

Bus = low frequency (1)


Frequency Light speed = 186,000 miles per second

Blue light waves = higher frequency

Red light waves = lower frequency


Frequency – Visible Light

Red light

Orange light

Yellow light

Green light

Blue light

Violet light


Frequency – Visible Light

The light we use to see has all of these wavelengths in it.


So . . . How Do We See Colors?

Let’s start with our eyes.

To Brain

Light waves

Light waves



If there is no light . . .

To Brain

Light waves

Light waves




To Brain




To Brain

you cannot see because there are no

light waves reflecting to your eye.Our eyes only see light reflected off things!



The green part absorbs all of the colors except green. It reflects green light.

To Brain

The red part absorbs all of the colors except red. It

reflects red light.


EMRThe light we see is part of a spectrum.

Rad

io

Mic

row

ave

Ultr

avio

let

Vis

ible

Infra

red

X-r

ay

Gam

ma

Ray

Electromagnetic Radiation Spectrum

K-12 Science, CCSD, 2006 Light Photos, sounds, and clipart were inserted from Microsoft’s Office...

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