Light…

One of our forms of energy (radiant)… what can we do with it… how

about without it???

Light… it is a wave

• Wave = repeating pattern– Waving good bye– Water waves– radio/tv/cell phones

Why don’t you draw one…

• Include: wavelength, amplitude, frequency

• Wavelength: length of the wave until it repeats.

• units = meters

• Frequency: how many wave lengths per second.

• Units = per seconds… or Hertz (Hz)• Why don’t you figure out the frequencies below.

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

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

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

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)

More??? more• 4. refraction (bend)

• 5. Diffraction – (spread through an opening)

• 6. Absorption – (stays in material)

• 7. Transmission – (pass through)

Properties of color

Color cool…. Sound good to…

Electromagnetic spectrum

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

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

screen

YARP!!!

MORE OPENINGS!!! YARP!!!

How your eye sees light

Cones for color cones for Red,

green, and blue

Rods for black and white

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

What animals are color blind?

• Have students guess before you click!!!• Dogs• Deer• Why do you think deer hunters wear blaze

orange???• yarp

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

The bars look kinda like this…

Desired color

Each color has 256 possibilities…

Move the bars up and down…

sound

Bringing back amplitude in a big way

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

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

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

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

Other cool things

Coolness of waves

Constructive and destructive interference

• How the waves line up is key.• Same frequency• Same amplitude• Jamming = destructive interference

• Same yarp

interference• Amplification = constructive interference• Circling signal through again and again to increase

the volume, intensity, etc…

• yarp

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

Sound decibels

• Logarithmic scale

What we can hear…

Volume: you need to increase the volume to hear at the blue line

Pitch… high number = high pitch

Feeling pain

equilizers

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…

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