Waves Contemporary Chemistry Mrs' Coyle

1
WavesContemporary ChemistryMrs. Coyle
2
Wave

• Wave a rythmic disturbance in both time and
  space.
• Waves transfer energy not matter.

3
Amplitude The distance from the equilibrium
(baseline) to the crest or trough)
l
4
Wavelength The distance from the crest to crest
or trough to trough.
l
5
Frequency the number of waves per second (Hertz,
Hz)
l
6
Low amplitude - High amplitude
7
Speed of a Wave

• v lf
• v speed
• l wavelength
• f frequency

8
Transverse Waves

• The particles vibrate perpendicular to the
  direction of the wave's propagation
• (ex waves along a string, electromagnetic
  waves).

9
Longitudinal Waves

• The particle displacement is parallel to the
  direction of wave propagation (ex sound)

10
Elliptical Waves

• Result when longitudinal and transverse waves
  are superpositioned.
• (ex surface water waves)

11
Torsional Waves

• Video link on Web
• http//www.youtube.com/watch?vP0Fi1VcbpAI

12
Wave Categories

• Mechanical Waves require a medium.
• Examples
• Water waves( Tsunami)
• Sound waves (f20-20000 hertz, v 340 m/sec in
  air but varies for different media, faster in
  solids)
• Earthquake waves
• Electromagnetic Waves do not require a medium.
  Can travel through space (vacuum).
• Example Light from the sun reaches us
• Note all EM waves have a speed through vacuum of
  3 x 108 m/sec.

13
Electromagnetic Waves

• Type of radiation Wavelengths(m)
• Radio 570 - 2.8
• TV 5.6 - 0.34
• Microwave 0.1 - 0.001
• Infrared radiation 10-3 - 10-7
• visible light
• red 700x10-9 (700nm)
• orange
• yellow
• green
• blue
• indigo
• violet 400x10-9 (400nm)
• ultraviolet 10-7 - 10-10
• x-rays 10-10 -10-12
• gamma rays shorter than 10-12

14
(No Transcript)
15
(No Transcript)
16
Note

• A waves speed is constant in a given medium. If
  you change the frequency of the wave, the
  wavelength will also change. If the frequency
  increases, the wavelength will decrease.
• When a wave travels from one medium to a
  different medium, the frequency remains the same
  and the speed changes.

17
Refraction
18
Dispersion
19
Diffraction
20
Remember my atomic model?
21
Niels Bohrs Atomic Model (1913)

• Electrons orbit the nucleus in circular paths of
  fixed energy (energy levels).

22
Niels Bohrs Atom Contd

• Electrons can jump from energy level to energy
  level.
• Electrons absorb or emit light energy when they
  jump from one energy level to another.

23
Hydrogen Emission Spectrum
Violet 410nm Blue 434nm Blue-Green 486
nm Red 656nm
Balmer Series
24
Bohr Model for Hydrogen