17.8 - Light Waves

Movement of Light Waves  Visible light is in the middle of the electromagnetic spectrum.

Movement of Light Waves ROY G. BIV (Red, orange, yellow, green, blue, indigo, violet) Red: Long wavelength : Low Frequency & Low Energy Violet: Short wavelength : High Frequency & High Energy

Movement of Light Waves Without light, nothing is visible   How light behaves when it strikes an object depends on many factors, including the material the object is made of. Materials can be transparent, translucent, or opaque.

Transparent A transparent material transmits light, which means it allows the light that strikes it to pass through it.

Transparent Examples: Glass Beaker Fish in Fishbowl Window on bus

Translucent Translucent material scatters light. You can see through the material, but the objects you see through do not look clear.

Translucent Examples: Frosted windows Wax Paper Plastic Cups

Opaque Material absorbs or reflects all of the light that strikes it.

Opaque Examples: Wood Metals Rocks

Interactions with Light When light encounters matter, some or all of the energy in the light can be transferred to the matter. When light strikes a new medium, the light can be reflected, absorbed, or transmitted.

Reflection Reflection happens when light waves bounce off a surface

Absorption Stopping light is called absorption When light hits most objects, some of the light bounces off and the rest is absorbed. What you see when you look at it is the light that bounces off of it. Smooth shiny objects reflect most of the light. Dull objects absorb most of the light that hits them and reflects the rest.

Absorption

Absorption and Color Why is a black car hotter than a white car in the summer? Remember light is energy. Heat is another form of energy. A white car reflects all wavelengths of light. A black car absorbs all wavelengths of light, absorbing the energy and turning it to heat.

Transmission Wavelengths that are not absorbed are transmitted When light is transmitted, it can be refracted, polarized, or scattered.

17.8 Assessment Question #1 Explain the differences between opaque, transparent, and translucent material. Name an example of each one.      Question #2 List three things that can happen when a light wave enters a new medium.

17.8 Assessment Question #3 What color do you see of all the visible light is absorbed in a material?   Question #4 What color do you see of all the visible light is reflected from the material? Question #5 Why do black objects get hotter quicker than white objects?