LIGHT S. O. L. 5. 3 Created by Lori Kessinger LIGHT S.O.L. 5.3 Created by Lori Kessinger 5th Grade Teacher Critzer Elementary 2007

Take a look around the classroom

Lights OFF! How well can you see now?

How do we see? Our eyes only see what light allows us to see. Objects we see either produce or reflect light.

What is Light? Light is not matter! You can never observe a piece of light at rest. Light is a form of energy. Light is a way of transferring energy. Ex: heat

Light Facts Light travels much faster than sound. It travels at 186 miles per second. It takes on 8 ½ minutes for the sun’s rays to reach Earth. Unlike sound, light can travel in a vacuum.

More Light Facts When light hits an object, it is either absorbed, reflected, or transmitted. Smooth, hard objects reflect light best. Mirrors are excellent reflectors!

Is light white? What appears in the sky when the sun comes out after a rainstorm? Why does this happen?

What causes rainbows? In a rainbow, raindrops in the air act as tiny prisms. Light enters the raindrop, reflects off of the side of the drop and exits. In the process, it is broken into a spectrum just like it is in a triangular glass prism, like this:

Is light white? Light appears to be white. However, it is actually made of many different colors. A prism separates the colors that make up white light. A prism is a triangular piece of cut and polished glass. http://www.physics.mun.ca/~jjerrett/dispersion/prism.html

Visible Spectrum ROY G BIV The visible spectrum is the band of different colored light waves that vibrate at various frequencies. The colors in the visible spectrum can be remembered using the acronym: Red Orange Yellow Green Blue Indigo Violet ROY G BIV BrainPOP

Does Light Travel? Light travels in a straight path called a light ray. Light rays are characterized by their waves. Red light has the longest wavelength. Violet has the shortest wavelength.

There are three parts to a light wave Wavelength – distance from one peak to another Peak – top of the wave Trough – bottom (valley) of the wave Frequency- the number of waves that occur in 1 second

Parts of a Wave

Bouncing Light When light BOUNCES off of a surface, it is called REFLECTION. Light reflects off at the exact same angle as the original light beam!

Law of Reflection When light hits a surface, the angle at which it is reflected is the same as the angle at which it strikes. Example: Bounce a ball to someone standing across from you.

Bending light When light is BENT it is called REFRACTION.

Through which materials do light travel best? TRANSPARENT objects let MOST of the light through. Examples: Transparency Clean water Siran wrap Window glass Air

Which materials allow SOME light to pass through? TRANSLUCENT Examples: Wax paper Tracing paper Empty soda bottle Frosted glass Tissue paper Notebook paper

What is the name of an object that allows NO light to pass through? OPAQUE Examples: Brick Wood Book Tin foil Table top

Convex Lens Always produce an upright image Makes things look larger Brings light rays together

Concave Lens Curved inward and forms many different images Spreads out light rays

Lenses in Our World Convex Lenses glasses microscopes telescopes Concave Lenses glasses movie projector cameras

Galileo Galilei 1564- 1642 Italian physicist who built the first telescope Discovered mountains on moon, moons of Jupiter and the Milky Way

Robert Hooke 1632- 1723 English researcher Constructed multiple lens microscope Discovered plant cells

Anton van Leeuwenhoek 1632-1723 Dutch scientist Improved microscope Discovered bacteria and protozoa

Isaac Newton 1642- 1727 Showed white light can be separated into visible spectrum with prism Built first reflecting telescope Studied modern optics

Thomas Edison 1847- 1931 Invented first practical light bulb