1. Waves: Light, Earthquakes, Analog vs. Digital # 20

2. Interactions of Waves Refraction – The bending of a wave due to the wave moving from one type of medium into another. Refraction – The bending of a wave due to the wave moving from one type of medium into another. Reflection – Bounce back wave Reflection – Bounce back wave

3. Reflection & Mirrors 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

4. Electromagnetic Radiation EMR requires no medium to travel so waves can travel thru a vacuum (such as outer space.) EMR requires no medium to travel so waves can travel thru a vacuum (such as outer space.) Speed (light and other types of EMS waves) Speed (light and other types of EMS waves) 300,000 kilometers /sec 300,000 kilometers /sec 186,000 miles /sec 186,000 miles /sec Consists of changing electric and magnetic fields Consists of changing electric and magnetic fields

5. Electromagnetic Waves Long wavelength : Low Frequency & Low Energy Long wavelength : Low Frequency & Low Energy Short wavelength : High Frequency & High Energy Short wavelength : High Frequency & High Energy

6. Radio & Microwaves Longest wavelengths & lowest frequency of the EMS Longest wavelengths & lowest frequency of the EMS Includes Am, FM and Television frequencies Includes Am, FM and Television frequencies

7. Microwave & Infrared EMR Microwave: used in microwave ovens & cellular phones Microwave: used in microwave ovens & cellular phones Infrared: Fast Food Heat Lamps, use as a night time surveillance tool. Infrared: Fast Food Heat Lamps, use as a night time surveillance tool.

8. Visible Light White light is a mixture of the entire visible light spectrum White light is a mixture of the entire visible light spectrum Interesting Fact: Visible light makes up less than 1% of the entire electromagnetic spectrum!

9. UV, Xray & Gamma rays UV from the Sun helps the body produce vitamin D, too much exposure can cause skin cancer UV from the Sun helps the body produce vitamin D, too much exposure can cause skin cancer Xrays: used extensively in medicine to see “into” the body Xrays: used extensively in medicine to see “into” the body Gamma Rays: used in medicine to treat cancer or destructive radiation from nuclear explosions. Gamma Rays: used in medicine to treat cancer or destructive radiation from nuclear explosions.

10. Seismic Waves Seismic Waves – waves caused by the release of energy due to earthquakes composed of Seismic Waves – waves caused by the release of energy due to earthquakes composed of P - primary waves P - primary waves S - secondary waves S - secondary waves L - surface waves L - surface waves

11. P & S Waves P waves –- (1 st wave) Primary waves are pressure waves & are the fastest moving waves, they travel thru solids and liquids, They’re “push-pull” or Longitudinal waves P waves –- (1 st wave) Primary waves are pressure waves & are the fastest moving waves, they travel thru solids and liquids, They’re “push-pull” or Longitudinal waves S Waves – (2 nd ) Secondary Waves are slower than primary waves, they cannot travel thru liquid and are Transverse Waves. S Waves – (2 nd ) Secondary Waves are slower than primary waves, they cannot travel thru liquid and are Transverse Waves.

13. L Waves L Waves (last waves) Surface wave – the combination on the Earth’s surface of Primary and Secondary waves. L Waves (last waves) Surface wave – the combination on the Earth’s surface of Primary and Secondary waves. The rolling chaotic movement of the surface The rolling chaotic movement of the surface Cause the most damage of the seismic waves Cause the most damage of the seismic waves

15. Analog vs. Digital 2 types of wave signals used to transmit information 2 types of wave signals used to transmit information Analog waves are smooth and continuous Digital waves are stepping, square, and unconnected.

16. Examples 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.