Electromagnetic Waves

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http//gtn.sonoma.edu/public/resources/presentati
ons/06_03_02/img003.jpg
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Electromagnetic Waves

• EM waves are created by vibrating electric
  charges. (electrons in atoms!)
• These do not need a medium because they travel by
  transferring energy between electric and magnetic
  fields.

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Electromagnetic Waves

• These electric and magnetic fields continually
  create one another allowing for EM waves to exist.

http//www.monos.leidenuniv.nl/smo/basics/images/
wave.gif
Click Here for a 3D EM Wave Demo
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EM Wave Properties

• The speed of an EM wave depends on the medium it
  is traveling through.
• As the medium becomes more dense, the speed
  decreases!

http//micro.magnet.fsu.edu/primer/java/speedofli
ght/javalightspeedfigure1.jpg
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EM Wave Properties

• In a vacuum, EM waves travel at 300,000,000 m/s.
• Air is 299,997,000 m/s so we will use 300,000,000
  m/s for simplicity.

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Scientific Notation

• Removes extra zeros from numbers to make them
  smaller.
• Example
• 300,000,000. m/s
• 3.0 x 108 m/s

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Scientific Notation

• Move decimal to the left positive exponent.
• 23,000,000.
• Left 7 spaces
• 2.3 x 107

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Scientific Notation

• Move decimal to the right negative exponent.
• 0.0000067
• Right 6 spaces
• 6.7 x 10-6

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Scientific Notation Calculations

• Multiplication
• Multiply the mantissas.
• Add the exponents.
• Mantissa must have only 1 number in front of the
  decimal.

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Scientific Notation Calculations

• Example
• (3.0 x 104) x (4.0 x 103)
• 12.0 x 107 , but the mantissa is bigger than 10
  so.
• 1.2 x 108

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Scientific Notation Calculations

• Division
• Divide the mantissas.
• Subtract the exponents.
• Mantissa must have only 1 number in front of the
  decimal.

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Scientific Notation Calculations

• Example
• (2.0 x 107) / (4.0 x 103)
• 0.5 x 104 , but the mantissa is less than 1 so
• 5.0 x 103

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Scientific Notation Calculators
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Scientific Notation Calculators

• Graphing or 2-line (6.67 x 10-11)

• Enter 6.67

• Press the EE Key

• Enter -11

• 6.67 x 10-11

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Scientific Notation Calculators

• One Line (3.71 x 10-5)

• Enter 3.71

• Press the EE Key or EXP Key

• Enter -5

• 3.71 x 10-5

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Scientific Notation Calculators

• For both calculators, when entering negative
  exponents use the negative key not the minus
  sign key!!!