physical science light. electromagnetic spectrum
Post on 19-Dec-2015
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TRANSCRIPT
Liquid Crystals
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No current - no alignmentCurrent - Alignment
Light can go throughno light gets through
White Light• The light coming from the sun is
what we call white light or a mixture of all colors
• Can be separated into it components with a prism
Addition of Light
• Blue and red = magenta (purplish color)• Green and blue = cyan (greenish blue)• Red and green = yellow
Mixing of Colors in Pigments
• Mixing of light different than mixing pigments
• When you mix paint, you mix small particles that absorb the complimentary color.
Mixing of Colors in Pigments
• The small particles in the pigment absorb specific colors and thus we see what is not absorbed.
• For instance, a paint that looks red has small particles in it that absorb cyan and thus reflects its complimentary color red.
Why is the Sky Blue
• Recall the tuning fork demo – one vibrating fork causes another to vibrate
• When light waves strike atoms in the atmosphere they cause them to scatter light (reemitted light in all directions)
Why is the Sky Blue
• The nitrogen a oxygen primarily scatter violet light
• Our eyes are not as sensitive to violet light so we see it mostly as blue
Why is the Sky Blue
• Water vapor effects the color – dry air – really blue
• Particles in the air tend to turn it grey or brown
• After a good rain, the sky seems deeper blue
Why are sunsets red?
• Light that isn’t scattered is transmitted through the air
• Red light is scattered the least and therefore transmitted the best
• The further light travels through the atmosphere, the more opportunity to be scattered
Why are sunsets red?
• If light passes a long way, more of the high frequency (blue) light is scattered and red becomes more predominate.
• When we look toward the sun at sunrise or sunset, we se light traveling through a lot of atmosphere
• So red is the predominate color to reach our eyes.
Why are clouds white
• Clouds contain clusters of water droplets in various sizes
• Different sized water clusters scatter light at different frequencies
• We see different frequencies as different colors
• If you have clusters producing red, green and blue – we see white
Why are clouds white
• Clouds also contain a large quantity of free electrons
• These electrons vibrating in step increase the intensity of the light therefore clouds tend to be bright