Waves: Light, Waves: Light, Earthquakes, Earthquakes,

Analog vs. Analog vs. DigitalDigital

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Interactions of WavesInteractions of Waves RefractionRefraction – – The bending of a wave due to the wave The bending of a wave due to the wave

moving from one type of medium into another.moving from one type of medium into another.

ReflectionReflection – – Bounce back waveBounce back wave

Reflection & Reflection & MirrorsMirrors

When light strikes an object it is either reflected, absorbed or transmitted. Opaque: a material that reflects or absorbs

the light – you can’t see through it. Ex) wood, concrete, walls, jackets

Translucent: allows some light to pass through – you can’t see image clearly.Ex) tinted windows, wax paper, frosted glass

Transparent: The material transmits light – you can see light through it.Ex) glass, lenses, air, diamonds

Electromagnetic Electromagnetic RadiationRadiation

EMR requires no medium to travel EMR requires no medium to travel so waves can travel thru a vacuum so waves can travel thru a vacuum (such as outer space.)(such as outer space.)

Speed (light and other types of EMS Speed (light and other types of EMS waves)waves)

300,000 kilometers /sec300,000 kilometers /sec 186,000 miles /sec186,000 miles /sec

Consists of changing electric and Consists of changing electric and magnetic fieldsmagnetic fields

Electromagnetic WavesElectromagnetic Waves Long wavelength : Low Frequency & Low EnergyLong wavelength : Low Frequency & Low Energy Short wavelength : High Frequency & High Energy Short wavelength : High Frequency & High Energy

Radio & MicrowavesRadio & Microwaves Longest wavelengths & Longest wavelengths &

lowest frequency lowest frequency of the of the EMSEMS

Includes Includes Am, FM and Am, FM and TelevisionTelevision frequencies frequencies

Microwave & Infrared Microwave & Infrared EMREMR

MicrowaveMicrowave: used in microwave ovens & cellular : used in microwave ovens & cellular phonesphones

InfraredInfrared: Fast Food Heat Lamps, use as a night : Fast Food Heat Lamps, use as a night time surveillance tool.time surveillance tool.

Visible LightVisible Light White light is a mixture of the entire visible light White light is a mixture of the entire visible light

spectrumspectrum

Interesting Fact: Visible light makes up less than 1% of the entire electromagnetic spectrum!

UV, Xray & Gamma raysUV, Xray & Gamma rays UVUV from the Sun helps the body produce vitamin D, too from the Sun helps the body produce vitamin D, too

much exposure can cause skin cancer much exposure can cause skin cancer XraysXrays: used extensively in medicine to see “into” the body: used extensively in medicine to see “into” the body Gamma RaysGamma Rays: used in medicine to treat cancer or : used in medicine to treat cancer or

destructive radiation from nuclear explosions.destructive radiation from nuclear explosions.

Seismic WavesSeismic Waves Seismic Waves Seismic Waves – – waves caused by waves caused by

the release of energy due to the release of energy due to earthquakes composed of earthquakes composed of P - primary wavesP - primary waves S - secondary wavesS - secondary waves L - surface wavesL - surface waves

P & S WavesP & S Waves P waves P waves –- (1–- (1stst wave) wave) Primary waves are pPrimary waves are pressure waves & ressure waves &

are the fastest moving waves, they travel thru solids and are the fastest moving waves, they travel thru solids and liquids, They’re “push-pull” or Longitudinal wavesliquids, They’re “push-pull” or Longitudinal waves

S Waves S Waves – (2– (2ndnd) ) Secondary Waves are slower than primary Secondary Waves are slower than primary waves, they cannot travel thru liquid and are Transverse waves, they cannot travel thru liquid and are Transverse Waves.Waves.

L WavesL Waves L Waves (last waves) Surface wave L Waves (last waves) Surface wave – – the the

combination on the Earthcombination on the Earth’’s surface of Primary s surface of Primary and Secondary waves. and Secondary waves. The rolling chaotic movement of the surfaceThe rolling chaotic movement of the surface Cause the most damage of the seismic wavesCause the most damage of the seismic waves

Analog vs. DigitalAnalog vs. Digital 2 types of wave signals used to transmit information2 types of wave signals used to transmit information Analog waves are smooth and continuous

Digital waves are stepping, square, and unconnected.

Examples of Analog vs DigitalExamples of Analog vs Digital 

Analog waves are more susceptible to interference and interruptions. Ex) Human voice, record player, old telephones, under the tongue thermometers    

Digital signals are most common in current technology: Computers, CDs, DVDs, and other digital electronic devices.