What is Light?

Light

• Look around you. What do you see?• You might say books, pencils, desks, chairs.• But what you really see is light bouncing off

books, pencils, desks, and chairs.• You can see objects only if they reflect light or

produce it themselves.• Light is a type of energy produced by the

vibration of electrically charged particles

Transmission of Light

• Sometimes light passes through matter.• Light passes through some materials more

easily than other.

Station 1 Transparent, Translucent, Opaque

• Transparent: Letting all light through, so that objects on the other side can be seen clearly.

• Examples – Transparency paper Glass

• Translucent : Letting only some light through, so that objects on the other side appear blurry.

• Examples – Tissue paper

• Stained glass

Station 1

• Opaque: completely blocking light from passing through it.

• Examples - calculator books wooden door

Station 2Prisms

• White light comes in to the classroom.

• You see the colors of the rainbow: ROYGBIV on the opposite side of the prism.

• A prism refracts light, breaking up a beam of white light into all the colors of the rainbow.

Station 3Reflection

• Reflection: the bouncing of waves off a surface. • You should see the light being reflected on the black

piece of paper through the opposite tube. • The beam of light hits the mirror and is reflected

through the other tube onto the black construction paper.

Station 4Reflection

• You should not see the light being reflected on the black piece of paper through the opposite tube.

• The beam of light hits the construction paper and is NOT reflected through the other tube onto the black construction paper. Paper does not have a smooth surface.

Station 5Refraction

• Refraction: the bending of waves as they go from one substance to another.

• The coin in the water disappeared last. This happened because the light hit the water and bent the image of the coin making it appear to be larger than the coin with out the water.

Station 6Refraction

• Light always travels in straight lines.• But when it passes from one medium to

another (from air to water), light changes direction slightly.

• The pencil looks like it is shifting position or broken because the light waves bend as they travel from air to the water.

Station 7Refraction Telescopes

• Not all of the rice made it into the cups.• The larger cup captured more rice because it’s

mouth was larger.

Refracting Telescope

A refracting telescope uses lenses to form and magnify an image of a faraway object. Light from a planet enters the refracting telescope and passes through a lens that bends and focuses the light rays. The rays then pass through another lens that enlarges the image seen with the eye.

Reflecting Telescope

A reflecting telescope uses mirrors and a lens to form and magnify an image of a faraway object. Light from a planet enters a reflecting telescope and is reflected off of a mirror and focused onto a flat angled mirror which reflects light through a lens that enlarges the image seen with the eye.

The Electromagnetic Spectrum

• Light travels in the form of electromagnetic waves.

• There are many types of electromagnetic waves, most of which cannot be detected by the human eye.

• Different types of electromagnetic waves are classified by their wavelength.

The Electromagnetic Spectrum

• A model to help you visualize how a light wave travels is to shake a string.

• If you shake a string continuously back and forth a wave travels through the string away from your hand.

• The distance from one peak to the next on a wave is called wavelength.

The Electromagnetic Spectrum

The Electromagnetic Spectrum• If you tie a flag to the string at any point. That

flag will vibrate as the wave passes through. • The number of waves that pass through any

point in a second is called the wave’s frequency.

The Electromagnetic Spectrum