Behavior of Light

Getting the Idea Light is another form of energy. You can see all the objects around you because the sun (or a lamp) is sending out light energy. Light travels in the form of waves. Light waves behave in predictable ways.

Light Waves Light waves move in a straight path called a ray. You can see a light’s straight path when you use a flashlight.

When light strikes an object, it either passes through the object or is blocked by the object; depending on what the object is made of. Light passes easily through transparent materials, such as clear glass and pure water. These materials transmit light or allow its passage.

Translucent materials, such as wax paper, scatter the light that they transmit. You cannot see clearly through translucent materials. Opaque materials, such as wood and metal, block light completely. You cannot see at all through opaque materials

Lenses A lens is a clear material that has at least one curved surface.

When light strikes a lens, its path changes – it bends. Lenses are shaped so that light that enters them bends and refocuses in a way that helps people see better. They are also used in microscopes, telescopes, and cameras.

A convex lens is thicker in the middle than at its edges. Light that enters a convex lens is bent inward. The light bends toward a point called the focus.

A concave lens has thicker edges and a thinner middle. Light that enters a concave lens is bent outward.

Refraction The bending of light is called refraction. Clear plastic, glass, and water all refract light.

Absorption and Reflection Only materials that transmit light can refract it. Other materials affect the path of light waves in different ways. Some materials change light energy into heat energy. This process is called absorption. The bouncing of light off a surface is called reflection. Everything we see reflects some light.

Test…Ready booklet #12, p. 6 #4, p. 15 # 16, p. 24 Light sources and light rays - enattack/flash/concepts/sourcesandrays.htmhttp:// enattack/flash/concepts/sourcesandrays.htm Reflection: seeing objects – enattack/flash/concepts/reflectionseeingobjects. htmhttp:// enattack/flash/concepts/reflectionseeingobjects. htm