Light and Color

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PROPERTIES OF LIGHT

1. Light Travels in Waves

2. Light behaves like a particle.

3. The speed of light is 300,000 km . per second.

Light Waves are Transverse Waves:

WAVELENGTH

WAVELENGTH

Frequency of Waves: The number of crests that pass one place each second.(Measured in Hertz)

Electromagnetic Radiation: Light in different frequencies and wavelengths.

X-rays : Have a short wavelength and therefore a

high frequency.

Radio Waves have longer wavelengths and therefore

lower frequency.

The visible spectrum of light is a small portion of the EMS.

Visible Light has 3 primary colors.

The Three Primary Colors of The Three Primary Colors of Light are Light are RedRed, , GreenGreen, and , and BlueBlue

Secondary colors are a mix of primary colors of light.

The Three Secondary Colors of Light The Three Secondary Colors of Light are are YellowYellow, , CyanCyan, , and and Magenta.Magenta.

Yellow, Cyan, and Magenta are the three primary pigments. These can be used to create any color of paint.

Mixing all three pigments together produces the color black. You may have

discovered this in art class or when mixing food colorings.

Black light is the absence of

light.

White Light is produced when the three primary colors of light are mixed.

A reflection occurs when a wave strikes an object and bounces off.

Angle of Incidence

Is Equal to the

Angle of Reflection

Question: Theoretically would light infinitely

bounce in a room made of perfect mirrors?

Answer: Yes, light would bounce forever in a room of

perfect mirrors. Unfortunately mirrors are not perfect and as

a result, not all light will be reflected. Eventually light intensity would decrease.

Refraction is the bending of light due to a change

in speed.

The speed at which light travels changes in materials of different

density. Thus changes in material cause light to refract.

Light from many sources, such as the sun, appears white. When white light passes through a prism, however, it separates into a spectrum of different colors. The prism bends, or refracts, light of different colors at different angles. Red light bends the least and violet light bends the most.

SUBSTANCE REFRACTIVE INDEX*Vacuum 1.0000Air 1.0003Ice 1.309Water 1.33Ethyl alcohol 1.36Glass (fused quartz) 1.46Glass (crown) 1.52Sodium chloride (salt) 1.54Zircon 1.92Diamond 2.42

* For light with a wavelength of 590 nm (590 x 10-9 m)

Diffraction: The bending of waves around a barrier. This

can best be seen by examining the outer edge of a shadow.

Despite what you may think, mirrors don’t make

copies of what you are looking at!

A good example of a pair of images that are

mirrored reflections are your left and right hand.

They are basically the same, but one is a reversed

version of the other.

The image appears to be beyond the mirror even though we know the mirror is opaque.

Concave Mirror with real object further than focal length.

Concave Mirror with real object closer than focal length.

Convex Mirror

Convex Lenses are thicker in the middle and thinner at the edges. These are used in projectors.

Concave lenses are thinner in the middle and make objects appear farther away. They are used to correct nearsighted vision..

A microscope uses two convex lenses to focus a

virtual image that may be hundreds of

times bigger than the real image.

The End!

We hope this presentation helped

you see the light!