April 6, 2005 Created by Kristy Lynn Price

LIGHTTLW explore what you see when you mix colors of light.

TLW describe visible light as a part of the electromagnetic spectrum.

TLW compare reflection and refraction of light.

TLW explain why we see the colors of objects.

April 6, 2005 Created by Kristy Lynn Price

What is Light?• A form of energy that travels in waves• What are two other sources of light on Earth?• White light is made up of all colors • A light is made up of waves• What is a wavelength? • A visible spectrum is the seven colors of light that make up white light• A spectrum is a range of light waves with different wavelengths and

energies • The electromagnetic spectrum is a range of all light waves with varying

wavelengths, including the visible spectrum (F42 and 43)

April 6, 2005 Created by Kristy Lynn Price

Waves

redwavelength

violet

Red has the longest wavelength

Violet has the shortest wavelength

April 6, 2005 Created by Kristy Lynn Price

How Does Light Travel?

• Shadows are places where light is blocked

• It takes the shape of whatever is blocking the light

• Shadows show that light travels in straight lines or rays

• Light cannot bend and go around things to create a shadow

• Index Cards Demonstration

April 6, 2005 Created by Kristy Lynn Price

What is Reflection?• When light strikes a surface, it bounces off

• Smooth, shiny surfaces reflect almost all the light reflecting on them

• Describe objects that reflect light well

• What happens to light when it is reflected?– It changes direction

when it is reflected off a surface

• Mirror demonstration of how rays bounce off a surface and change direction

April 6, 2005 Created by Kristy Lynn Price

What is Refraction?• Glass of Water/Pencil Demonstration

• Refraction is the bending of light as it passes from one material to another

• It happens when light passes through glass, water, light plastic, and other transparent materials

• What do you think causes refraction?– Light traveling at different speeds in different objects

• Remember: LIGHT RAYS DO NOT CURVE

• The ray changes direction as it passes from one material to another

April 6, 2005 Created by Kristy Lynn Price

Types of Lenses• What objects use lenses?

• Convex– Bulge in the middle– Makes objects bigger– Magnifying glass

• Concave– Curves inward

April 6, 2005 Created by Kristy Lynn Price

Review• What is the electromagnetic spectrum?• Why do shadows form?• What happens to light when it strikes the

surface?• Describe the difference in how light is

reflected off of smooth and rough surfaces.• What is the difference between concave and

convex lenses?• When does refraction occur?