Interactions of Light Waves and Matter

Interactions of Light Waves and Matter When light strikes any form of matter, it can interact with the matter in three ways: It can be reflected. It can be absorbed. It can be transmitted. Or most likely, some combination of these happens.

Absorption of Light Absorption (in optics): the transfer of light energy to particles of matter What happens to the matter that absorbs the light energy? Answer It gains heat energy. How do you know? Which cat will feel warmer in the sun?

Scattering of Light Scattering is an interaction of light with matter that causes light to change its energy, direction of motion, or both. Light is scattered when it is absorbed by matter and then emitted in different directions. Find out how scattering makes the sky blue. Read: http://www.sciencemadesimple.com/sky_blue.html

Transmission of Light Transmission is the passing of light or other forms of energy through matter. Light is easily transmitted through transparent substances. Translucent substances transmit some of the light and absorb or scatter some of the light. Opaque substances absorb and/or reflect all the light.

Refraction Bill Nye the Science Guy on Refraction http://www.youtube.com/watch?v=fD1544bM_c4

Refraction Refraction is the bending of a wave when it enters a medium where its speed is different. The wave must be entering the new medium at an angle for this to happen.

Refraction and Optical Illusions

Refraction and Optical Illusions Magnifying Glass http://www.youtube.com/watch?v=ACFCVFCoYpE Invisible iBalls http://www.youtube.com/watch?v=R-Baho45vlg Making a Penny Disappear http://www.youtube.com/watch?v=kujevo3rCLI Disappearing Bottle http://www.youtube.com/watch?v=_QyFqoERPts Do the disappearing penny activity

Colors of Light Ludwig Von Drake http://www.youtube.com/watch?v=arZRYbtb20M&feature=related Bill Nye: Light and Color http://www.youtube.com/watch?v=gtgBHsSzCPE&feature=related

Visible Light Visible light is the very narrow range of wavelengths and frequencies in the electromagnetic spectrum that humans can see. Visible light waves have wavelengths between 400 nm and 700 nm. ROY G BiV

Prisms A prism is an example of refraction in action. When light is refracted, the amount that the light bends depends on its wavelength. Waves with short wavelengths bend more than waves with longer wavelengths. Experiment with prisms

Adding Colors of Light SciZone - Ontario Science Centre: Mixing Colours Primary Light Colors: Blue, Green, and Red Secondary Light Colors: Cyan, Magenta, and Yellow Use three color lights to demonstrate

The Color of Opaque Objects The color of an object is determined by what color or colors it reflects. What colors are reflected by the following objects?

Pigments A pigment is a substance that gives another substance or mixture its color. Two examples: Chlorophyll – makes leaves green Melanin – give skin its color

Pigments Primary pigment colors: Yellow, Cyan, and Magenta – these combine to make black Secondary Pigments: Green, Blue, and Red

Color Subtraction Each pigment absorbs at least one color of light. When you mix pigments together, more colors are absorbed or taken away so mixing pigments is called color subtraction. Recall the experiment where we separated black ink into red and blue and green ink into yellow and blue.

Diffraction Diffraction is the bending of waves around barriers or though openings. The amount a wave diffracts depends on its wavelength and the size of the barrier or opening. Demonstrate with diffraction grating

Diffraction http://www.youtube.com/watch?v=kH57Di7Sj0c

Interference Interference is the combination of two or more waves that results in a single wave In constructive interference the resulting wave has a greater amplitude than the original waves had. In destructive interference the resulting wave has a smaller amplitude than the original waves had. Interference can cause bright and dark bands to form.