Light…
description
Transcript of Light…
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Light…
One of our forms of energy (radiant)… what can we do with it… how
about without it???
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Light… it is a wave
• Wave = repeating pattern– Waving good bye– Water waves– radio/tv/cell phones
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Why don’t you draw one…
• Include: wavelength, amplitude, frequency
• Wavelength: length of the wave until it repeats.
• units = meters
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• Frequency: how many wave lengths per second.
• Units = per seconds… or Hertz (Hz)• Why don’t you figure out the frequencies below.
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How is frequency used?• Frequency can identify any electromagnetic
wave based off of how many times it repeats itself every second.
• Radio stations: 98.6 FM (MHz = megahertz)• Any other signal… synchronizing remotes,
wireless video game controllers, cell phones, internet
• Tells us how much energy the wave has• The wavelength can also do this.• yarp
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What about amplitude?
• Intensity• Sound = volume
• Bigger the speaker, the louder the sound (old school)• This allowed for more squish and stretch (back and
forth movement can be seen in the speaker)• There are other ways to get more volume
• light = brightness• Yarp = yarpness
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How do waves move???
• Use a slinky if you got one around• Transverse = up and down• Ex. Electromagnetic spectrum• Longitudinal = squish and stretch• Sound• yarp
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How waves move draw em…• Hope you got the laser, mirror, wawa and
overhead ready• 1. plane waves (straight)
• 2. circular waves (ripple)
• 3. Reflect (bounce)
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More??? more• 4. refraction (bend)
• 5. Diffraction – (spread through an opening)
• 6. Absorption – (stays in material)
• 7. Transmission – (pass through)
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Properties of color
Color cool…. Sound good to…
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Electromagnetic spectrum
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Speed of light
• All electromagnetic waves move the speed of light
• 3 x 108 m/sec• Circle the earth 27 times in 1 second• It is constant…• Can “slow” it down in different materials• yarp
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Light colors add together• Red, green, blue = 3 primary colors• All together make white…• Different intensities and combinations of each
make all different colors….• red + green = yellow• blue + green = light blue (cyan)• Red + blue = light pink/red (magenta)• Colors overlap to make new colors• yarp
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screen
YARP!!!
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MORE OPENINGS!!! YARP!!!
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How your eye sees light
Cones for color cones for Red,
green, and blue
Rods for black and white
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coolness• Cone cells for color need more light intensity• Rod cells (black and white) work well in low
light intensity…• That is why at night things are less colorful and
more black and white• Color blindness is because one or more of
your cone cells are missing/not working• Red cone cells are common to miss• yarp
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What animals are color blind?
• Have students guess before you click!!!• Dogs• Deer• Why do you think deer hunters wear blaze
orange???• yarp
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The development of computer screens• Old screens… green• CGA screens = 4 colors– Yellow and red OR blue and black
• VGA screens = 256 color intensities for a pixel• Now… 256 color intensities for EACH COLOR– 256 Red x 256 green x 256 blue
• 16,777,216 color combinations• Customizing virtual “avatars” with color bars• yarp
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The bars look kinda like this…
Desired color
Each color has 256 possibilities…
Move the bars up and down…
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sound
Bringing back amplitude in a big way
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sound
• Sound waves caused by vibration of materials• No material, no sound– In space no sound (outside your helmet)
• A longitudinal wave (squish stretch)• yarp
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Speed of sound• Changes for different materials• Air sea level = 344 m/sec• Air mountain top = 330 m/sec• Air hot desert = 360 m/sec• Water = 1500 m/sec• Iron = 5960 m/sec• Old string can phone• Yarp = faster than speed of light
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More on sound…
• Frequency = pitch, specific note heard– More frequent = higher pitch– Less frequent = lower pitch
• Amplitude = volume• How far back and forth the speaker can
physically move• yarp
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Show amplitude with this imagePlastic or paper old
schoolVoice coil has electricity
going through it to change it’s magnetic
field. Moving it forward or backwards based on the magnet moving the
cone to push air and make sound
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Other cool things
Coolness of waves
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Constructive and destructive interference
• How the waves line up is key.• Same frequency• Same amplitude• Jamming = destructive interference
• Same yarp
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interference• Amplification = constructive interference• Circling signal through again and again to increase
the volume, intensity, etc…
• yarp
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Doppler effect• Squishing or stretching to change the
frequency of a wave.• This can be done by moving the source of the
signal… • Or bouncing off of moving objects to get your
signal returned… speeding radar.• Check out your sweet web site… for a couple
of these• yarp
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Sound decibels
• Logarithmic scale
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What we can hear…
Volume: you need to increase the volume to hear at the blue line
Pitch… high number = high pitch
Feeling pain
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equilizers
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polarization
• When electromagnetic waves come in at different angles… use thin openings…
• To block certain• Parts of the wave• Draw it…• Show it…• Yarp it…
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filters• Color filters allow only certain frequencies of
light to pass through… • Red filters allow red light to pass (you see it)• It absorbs the rest of the colors….• Why don’t you show em the glow in the dark
dealy….??? Maybe later?• yarp