i. electromagnetic waves
TRANSCRIPT
I. Electromagnetic WavesI. Electromagnetic Waves
Waves… a reviewWaves… a review
Most waves are either longitudinal or Most waves are either longitudinal or transverse.transverse.
Sound waves are longitudinal.Sound waves are longitudinal.But *But *all all electromagneticelectromagnetic waves are waves are
transversetransverse……
?
?
1.1. When an electric field changes, so does the When an electric field changes, so does the magnetic field. When one field vibrates—so magnetic field. When one field vibrates—so does the other.does the other.
2.2. RESULT-RESULT- An An electromagneticelectromagnetic
wave.wave.
Click here Click here Animation: Interaction of Animation: Interaction of vibrating chargesvibrating charges
A. Electromagnetic wavesA. Electromagnetic waves1.1. Produced by the movement of electrically Produced by the movement of electrically
charged particlescharged particles
2.2. Can travel in a “vacuum” (they do NOT Can travel in a “vacuum” (they do NOT need a medium)need a medium)
3.3. Travel at the speed of Travel at the speed of
light: 300,000,000 meters/second light: 300,000,000 meters/second (Takes light 8 minutes to move from(Takes light 8 minutes to move from
the sun to earth {150 million miles} the sun to earth {150 million miles}
at this speed.)at this speed.)
(Also known as EM waves)(Also known as EM waves)
Waves of the Electromagnetic SpectrumWaves of the Electromagnetic Spectrum Electromagnetic SpectrumElectromagnetic Spectrum—name for the range of —name for the range of
electromagnetic waves when placed in order of increasing electromagnetic waves when placed in order of increasing frequencyfrequency
Click here Click here ((AnimationAnimation—Size of EMwaves—Size of EMwaves))
RADIO WAVES
MICROWAVES
INFRARED RAYS
VISIBLE LIGHT
ULTRAVIOLET RAYS
X-RAYS
GAMMA RAYS
Wave-particle DualityWave-particle Duality
Light can behave like a wave or like a Light can behave like a wave or like a particleparticle
A “particle” of light is called a A “particle” of light is called a photonphoton
Radio wavesRadio wavesHave the Have the longestlongest wavelengths and wavelengths and
lowest lowest frequencies of all the frequencies of all the electromagnetic waves.electromagnetic waves.
Uses:Uses:TV broadcastingTV broadcastingAM and FM broadcast radio ( each channel is AM and FM broadcast radio ( each channel is
a different frequency)a different frequency)Cell phone communicationCell phone communication
MicrowavesMicrowaves
Wavelengths from 1 mm- 1 mWavelengths from 1 mm- 1 mUses:Uses:
Microwave ovensMicrowave ovensBluetooth headsetsBluetooth headsetsBroadband Wireless InternetBroadband Wireless InternetRadarRadarGPSGPS
How does a microwave oven work?How does a microwave oven work?
Waves transfer energy to the water in the Waves transfer energy to the water in the food causing them to vibrate which in turn food causing them to vibrate which in turn transfers energy in the form of heat to the transfers energy in the form of heat to the food.)food.)
Infrared RadiationInfrared Radiation
Wavelengths in between microwaves and Wavelengths in between microwaves and visible lightvisible light
Uses:Uses:Night vision gogglesNight vision gogglesRemote controlsRemote controlsHeat-seeking missilesHeat-seeking missiles
Visible lightVisible light
Only type of EM wave able to be detected Only type of EM wave able to be detected by the human eyeby the human eye
Violet is the highest frequency lightViolet is the highest frequency lightRed light is the lowest frequency lightRed light is the lowest frequency light
UltravioletUltraviolet
Shorter wavelengths than visible lightShorter wavelengths than visible lightUses:Uses:
Black lightsBlack lightsSterilizing medical equipmentSterilizing medical equipmentWater disinfectionWater disinfectionSecurity images on moneySecurity images on money
Ultraviolet (cont.)Ultraviolet (cont.)
UVAUVA UVB and UVCUVB and UVC
EnergyEnergy Highest of UV Highest of UV waves waves
Lower than UVALower than UVA
Health Health risksrisks
Extremely low Extremely low risk for DNA risk for DNA damagedamage Can destroy Can destroy Vitamin A in skinVitamin A in skin
Can cause DNA Can cause DNA damage, leading to damage, leading to skin cancerskin cancer Responsible for Responsible for sunburnsunburn
X-raysX-rays
Tiny wavelength, high Tiny wavelength, high
energy wavesenergy wavesUses:Uses:
Medical imagingMedical imagingAirport securityAirport security Inspecting industrial weldsInspecting industrial welds
Gamma RaysGamma Rays
Smallest wavelengths, highest energy EM Smallest wavelengths, highest energy EM waveswaves
UsesUsesFood irradiationFood irradiationCancer treatmentCancer treatmentTreating wood flooringTreating wood flooring
Using the EM waves to view the Using the EM waves to view the SunSun
Animation—View a Galaxy at different Animation—View a Galaxy at different wavelengthswavelengths
Brief SUMMARYBrief SUMMARYA. All electromagnetic wavesA. All electromagnetic waves travel at the travel at the
same speed. (300,000,000 meters/second same speed. (300,000,000 meters/second in a vacuum.in a vacuum.
B. They all have different B. They all have different wavelengthwavelength and and different different frequencies.frequencies.Long wavelength-Long wavelength-lowest frequencylowest frequencyShort wavelengthShort wavelength highest frequency highest frequencyThe higher the frequency the The higher the frequency the higher the higher the
energy.energy.