Electromagnetic Waves

Electromagnetic WavesCh 18.11TrueFalseStatementTrueFalseElectromagnetic waves are longitudinal waves consisting of electric and magnetic fieldsElectromagnetic waves can travel though all mediums and through a vacuum/empty spaceElectromagnetic waves travel as fast as the speed of lightElectromagnetic radiation can behave like waves and like particlesIntensity of light increases as the photons travel farther from the source2Electromagnetic WavesTransverse waves consisting of changing electric and magnetic fields

3Electromagnetic WavesProduced by:Travel by:An electric charge vibrating or accelerating

Electric field- produced by charged particles & magnetic fieldsMagnetic field- produced by magnets, by changing electric fields & vibrating chargesVacuum or empty space, as well as matterMagnetic fields and electric fields regenerate each othertraveling in the form of a wave

Electromagnetic RadiationTransfer of electromagnetic waves through matter4Speed of Electromagnetic WavesMichelsons ExperimentSpeed of LightUsed mirrors to calculate the speed of light

Light is faster than soundLighting 1stThunder 2nd

3.00 x 108 m/sWhen in a vacuum Same for electromagnetic waves

5Wavelength & FrequencyIn a vacuum all electromagnetic waves travel at the same speedOutside Different wavelengths and frequenciesSI UnitsV= f = Hz= m

6Math Practice1.

3.2.7Wave or Particle?Electromagnetic radiation behaves sometimeslike waves and like a stream of particles

8Waves and ParticlesWave ModelParticle ModelBright Bands indicate constructive interference

Dark Bands indicate destructive interferencePhoton- packets of electromagnetic energyBlue light high frequency photonEmission of electronsRed light- lower frequency photonNo emission of electrons

9IntensityRate at which a waves energy flows through a given area

Decreases as photons travel farther from the source10Electromagnetic SpectrumCh 18.211TrueFalseStatementTrueFalseRadio waves include microwaves, tv, and radar waves- which have the longest wavelengths=low frequencyInfrared rays can be felt by your skin, and can be very harmfulUltraviolet rays help your body produce vitamin D, which helps absorb CaXrays are absorbed by bones and too much can kill living tissueGamma rays are used to kill cancer cells12

Waves of the SpectrumElectromagnetic SpectrumFull range of frequencies of electromagnetic radiationIncludes:13Radio WavesLongest wavelengths in the spectrumLowest frequencies300,000 MHz or less

14Radio WavesRadioTelevisionAmplitude modulation (AM)Amplitude is varied, frequency stays the same

Frequency modulation (FM)Frequency is varied, amplitude stays the sameWeather and location can affect reception of signal

15Radio WavesMicrowavesRadarShortest radio wave

Penetrate food only to a few centimetersAlso carry cell phone conversationsRadio Detection and RangingDoppler EffectRadio waves are sent out, reflected, bounce back and picked up by a receiver

16Infrared RaysHigher frequencies than radioLower than red light

Used as a source of heat or to detect heat differencesCant see it but can feel its warmthThermograms

17Visible LightUltraviolet LightLight that the human eye can see

Higher frequencies than violet lightIn moderationHelp skin produce vitamin D, which helps absorb CaIn excessCauses sunburn, skin cancer, wrinklesKill microorganisims

18X RaysGamma RaysVery short wavelength, higher frequencies than ultraviolet

Bone and teethAbsorb Xrays , show densitiesToo much exposureKills living tissueShortest wavelengths, highest frequencies

Used to kill cancer cells, and take pictures of the brain

Overexposuredeadly

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20Behaviors of LightCh 18.321TrueFalseStatementTrueFalseMaterials can be transparent, translucent or opaqueDiffuse reflection is due to reflection off of a rough surfaceA mirage is a false or distorted image due to reflectionPolarization waves vibrate in all direction unlike normal light that vibrates in one planeScattering of light is why the sky looks blue, clouds look white, and the sun setting looks red22Light and MaterialsWithout light, nothing is visibleTransparent MaterialTransmits light (light passes through)

Translucent MaterialScatters light Can see through object, but looks cloudyOpaque MaterialAbsorb or reflect lightNo light passes through

23Interactions of LightWhen light strikes a new medium the light can beReflectedAbsorbedTransmittedRefractedPolarizedScattered24Interactions of LightReflectionRefractionRegular ReflectionParallel light strikes a surface and reflect all in the same directionDiffuse ReflectionParallel light strikes a rough, uneven surface and reflect in many different directionCause miragesFalse distorted imagesOccur becauseLight travels faster in hot air than cold

25Interactions of LightPolarizationScatteringLight with waves that vibrate in only one planeLight is redirected as it passes through a mediumSunrise/SunsetTiny particles scatter blue light- you see the red light

Blue SkyBlue light is scattered in all directions- blue sky even though colorless

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27ColorCh 18.428TrueFalseStatementTrueFalseWhite light separates into the color spectrum(ROYGBIV)Color of an object depends only on what color of light shines on the objectPrimary Colors of light at red, blue and green, while primary pigments are cyan, yellow and magentaA primary color + a secondary color = white lightA pigment + a pigment = black pigment29White Light = ColorsWhite light passes through a prism Shorter wavelengths refract more than longer wavelengths The colors separateProcess of white light separating into colorsDispersion

30Colors of ObjectsColor depends onWhat the object is made ofThe color of light that strikes the object

31Mixing Colors of LightPrimaryRed, Green, BlueIf both light colors hit a surface, they mix to form a new colorSecondaryCyan, Yellow, MagentaPrimary+Secondary=WhiteComplimentary color of light

32Mixing PigmentsPigmentReflects some colorsAbsorbs some colorsPaints, inks, dyes, photosPrimary PigmentsSecondary ColorsCyan, Yellow, Magenta2 Pigments= BlackComplementary Colors of Pigments

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34Sources of LightCh 18.535TrueFalseStatementTrueFalseA luminous object glows when light is shined on itAn incandescent light (light bulb) has a filament, while a fluorescent light (energy efficient) has photonsA laser also has photons, but emits radiationNeon lights color depends on the color of the tubeSodium vapor and tungsten halogen lights are the same36LightLuminousObjects that give off their own lightSun, flashlights, fireflies

37Types of LightIncandescentFluorescent Object gets hot enough to glowElectrons flow through the filament of the bulbThe filament gets hot and emits lightAbsorbs light at one wavelength, emits light at longer wavelengthPhosphor- solid that emits light by steadily emitting photons

38Types of LightLaser NeonLight Amplification by Stimulated Emission of RadiationGenerates a beam of coherent lightSolid, liquid or gas emits photonsEmit light when electrons move through a gas or mixture of gases inside glass tubing

39Types of LightSodium VaporTungsten HalogenSolid sodium, with neon and argon gasElectric current passes bulb, it ionizes, heats up and causes sodium to turn into a gasElectrons flow through a tungsten filament, which gets hot and emits light

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