Term
| What is the speed of light? |
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Definition
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o Nothing travels faster than light, 186,000 miles/second
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Term
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Definition
o A wave is a propagating disturbance through a medium
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Term
| What happens when 2 waves meet? |
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Definition
Constructive interference:2 waves meet, make a bigger wave, and continue on their way |
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Term
| What is destructive interference? |
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Definition
| Opposite crest and trough cancel out |
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Term
| What does in phase mean? Light/dark? |
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Definition
| It is constructive, they match up and make a bigger wave and is light |
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Term
| What does out of phase mean? |
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Definition
| They are opposite and cancel eachother out and is dark |
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Term
| In terms of amplitude, what is bright, dim, and no light? |
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Definition
Large amplitude =bright
Low amplitude=dim
zero amplitude=no light |
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Term
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Definition
| distance between two successive peaks |
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Term
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Definition
| Number of peaks passing per second. |
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Term
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Definition
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Term
| How do you find the speed of a wave? |
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Definition
| Speed = wavelength x frequency |
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Term
| What is the fastest traveling EM wave? |
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Definition
| They all travel at the same speed but have different wavelengths |
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Term
| What is the progression of wave lengths for EM waves? |
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Definition
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o Cosmic rays-gamma rays-xrays-ultra violet rays-visible light-infared-satellite communications-weather satellites-cellular phones-television-FM radio-AM radio-radio navigation-power transmission
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Term
| What is resonant frequency? What happens? |
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Definition
| The frequency in which they like to be shaken. If the wave shakes the object at its resonant frequency than it absorbs that energy |
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Term
| What happens when it is on resonance? Off resonance? |
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Definition
On resonance- wave absorbed
Off resonance- wave transmitted |
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Term
| What can you use gamma rays for? |
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Definition
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o borderline protection(looking for nuclear things), see blood flow, nuclear explosions, sendoff rockets(could)
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Term
| What can you use xrays for? |
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Definition
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o Xrays: on resonance with skin off resonance with bone so you can see bone not skin, CAT Scan, see teeth(on resonance), see tumors, see black holes, tell where ozone is
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Term
| What can you do with UV rays? |
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Definition
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o Ultra-violet: skin is on-resonance (waves aborbed by skin/skin burn/skin tan) eye lens is on resonance(waves absorbed by lens/don’t reach the retina(can’t see UV). Water is on resonance. We give off UV b/c we’re hot and environment is cold,
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Term
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Definition
| Smaller wavelengths, causes skin burn, doesn't pass through glass |
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Term
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Definition
| Longer wavelengths, doesn't cause skin burn, passes through glass |
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Term
| What does visible light do? |
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Definition
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o Visible light: the narrow range of wavelenths which are on resonance for the human retina. Different wavelengths are on resonance for different photo recpetors allowing us to see color. 400nm-700nm
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Term
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Definition
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o Infra-red: human skin is on resonance(waves absorbed by skin, energy rises, skin feels warm) human retina is off resonance(waves pass thru with no interaction, we don’t see it) liquid is on resonance. Makes us feel warm. Insects can see it because they don’t have liquid eyes. Remotes use it, they use it for eye exams, detect radiation, see warm and cold currents, see if you are lying
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Term
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Definition
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o Microwaves: shakes the water to heat it up, defrost means less amplitude, water is on resonance, absorbs energy, heats up. (more efficient than conventional ovens which heat air)
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Term
| How can you use radiowaves? |
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Definition
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o Radiowaves: radar (the time it takes it to come back tells the chip the speed of the car), soundwaves are sent out to detect objects under water-sonar, Whales use sonar to see, AM (amplitude modulated) FM (frequency modulated), can see through clouds up to 1m, radar used to detect storm front b/c they bounce off clouds with 100km wavelength so you can map where the clouds are
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Term
| What happens when you raise the temperature? |
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Definition
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o Raise temperature-charges wiggle faster-wave frequency increases. As you raise temp, glows red than orange, can determine temp from color. Increase temp-range of frequency increase-eventually white light.
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Term
| What type of light passes through clouds? |
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Definition
| UV passes through clouds, visible light doesn't |
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Term
| What happens when radiation passes through the atmosphere? |
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Definition
| Much of the IF is absorbed in the water of the atmosphere |
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Term
| What happens to the UV in the atmosphere? |
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Definition
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Term
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Definition
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Term
| What is the greenhouse effect? |
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Definition
| Light passes in and is absorbed by the plant, the plant gives off infrared, the infrared wont pass through the glass and that creates the heat. UV can't pass thru glass either |
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Term
| How is the greenhouse effect applied to global warming? |
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Definition
| The carbon dioxide acts like glass |
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Term
| How does light make color? |
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Definition
| It has to go through the atmosphere |
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Term
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Definition
| Heat up an object and gives off light ex.the sun, coal |
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Term
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Definition
| Electrons accelerated by voltage, smash into carbon plate, heating it up. Very bright, used in theaters |
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Term
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Definition
| Incandescent. Electrical resistance causes filament to warm up, filament then radiates. Very inefficient because it peaks in the infra-red |
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Term
| What is a tungsten-halogen light? |
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Definition
| Higher temperature with a containing halogen which makes the filament take longer to evaporate |
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Term
| Which light is "good light" and why? |
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Definition
| florescent because it radiates more light, less heat, voltage causes electrons to accelerate hitting gas molecules, causing them to wiggle. The molecule wiggles at its resonant frequency gives off light at the resonant frequency |
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Term
| What type of color do these gasses give off? Neon? Mercury? Krypton? |
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Definition
| Neon= red-orange. Mercury=blue-green, Krypton= pale blue |
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Term
| What are high intensity discharge lamps? |
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Definition
| Mercury lamps. Last 1000 years. Pale blue tint that lasts really long, only light no heat, efficient but mercury is really toxic |
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Term
| What is a florescent tube? |
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Definition
| Not incandescent, the shaking creates light. Electrode voltage accelerates electrons. These collide with gas molecules which shake on resonance, giving off UV radiation, phosphorous coating converts UV to visible |
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Term
| Why don't people like florescent light? |
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Definition
| It is more harsh, it gives out radiation at specific times unlike tungsten which is steady like the sun |
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Term
| When do you use florescence? |
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Definition
| For tagging molecules, art authenticity, police finger printing, and find it in nature |
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Term
| Where do you find natural light that is not incandescent? |
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Definition
| Lightening is not incandescent it is more like the efficient tubes, doesn't require heat for light. The northern lights aren't incandescent either |
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