Frequency and Wavelength are walking down a street. Frequency, being the clumsy one, stubs his toe on a rock and yells in pain. Wavelength asks, Are

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1 Frequency and Wavelength are walking down a street. Frequency, being the clumsy one, stubs his toe on a rock and yells in pain. Wavelength asks, Are you okay? Frequency replies, I ll live, but it Hz!

2 Waves Wave Properties Electromagnetic (EM) spectrum

3 Wave = Periodically repeating disturbance Examples Waves

4 Periodically repeating disturbance Example sister

5 Wave Properties (How to describe waves)

6 Some general wave properties 1. Velocity (speed) Define: How fast the wave moves, or Distance/time

7 Some general wave properties 1. Velocity (speed) Definition: How fast Symbol: v Units: m/s, mi/h (MPH), ft/s, Note: m vs mi

8 Some general wave properties 1. Velocity (speed) Symbol: v Units: m/s, mi/h, ft/s,... Examples: Light waves in space = mi/s Speed of sound in air = 1100 ft/s

9 Some general wave properties 2. Wavelength Define: Distance between similar points on a wave in the direction of wave travel Wave Moves Waves

10 Some general wave properties 2. Wavelength Definition: Distance between Symbol: (lambda) Units: m, mi, ft..., nm, m, Ångstrom (1 Å = m) Examples: Red light = 700 nm = 7000 Å Blue (violet) = 400 nm = 4000 Å Middle C = ~1 m Use longer and shorter to describe. Example-Red light has a longer then blue. Waves

11 3. Frequency Some general wave properties Define: Number of oscillations per second Waves

12 Some general wave properties 3. Frequency Symbol: f Units: cycles per second (cps), Hertz (Hz) = 1 cps Example: 88.5 MHz Middle C f ~ 330 Hz For sound, frequency corresponds to pitch. Use high and low to describe frequency and pitch. Example-Sopranos sing at high frequencies but basses sing at low frequencies. Waves

13 Some general wave properties 4. Energy Define: Ability to make something happen

14 Describing waves Demo, sound How are f and pitch related? How are f and λ related?

15 Describing waves Write a sentence or two comparing the wavelength and frequency of a higher pitch sound to a lower pitch sound. Use the Words Higher Lower Longer Shorter Frequency Wavelength

16 Describing waves Hearing check

17 Which is hotter? A reddish star or a blueish star?

18 Demo Heat metal rod with torch YouTube video of demo Observe: Flame and rod

19 Demo Heat metal rod with torch Observations: Before heating: Flame blue While heating: Blue flame below rod, yellow flame above As rod heated: Red to Orange to Yel/Or As rod cooled: Yel/Or to Orange to Red to warm

20 Demo Heat metal rod with torch Conclusions: Cooler to warmer: Red Orange Yellow - Blue

21 Demo Heat metal rod with torch Conclusions: Blue is hot, Red is cooler Order of colors from cooler to hotter is: Red Orange Yellow Green Blue Violet ROY G BIV

22 Which is hotter? A reddish star or a blueish star?

23 High temperature means fast vibes of atoms means high f means short λ Red Orange Yellow Green Blue Violet ROY G. BIV Longer λ (700 nm) Lower f Lower energy Lower temperature Shorter λ (400 nm) Higher f Higher energy Higher temperature

24 Describing waves Write a sentence or two comparing the energy, temperature, frequency and wavelength of a reddish star to a bluish star. Use the words Higher Lower Longer Shorter Frequency Wavelength Energy Temperature.

25 How color is used In some visual portrayals, (art or representations of intensity), red is intense and blue is less so. Waves

26 How color is used - Centaurus A Visible Radio Red is intense and blue is less so. Waves

27 How color is used Mars -- Red is high and blue is low. Waves

28 How color is used NGC Read the caption Waves

29 Spectra Radiation and Spectra

30 Spectra Spectrum display of color or wavelengths Spectra - plural

31 Electromagnetic (EM) Spectrum Visible ROY Spectra G. BIV Long λ (700 nm) (400 nm) Short λ Low f High f Low energy High energy

32 Electromagnetic (EM) Spectrum Visible ROY Spectra G. BIV Long λ (700 nm) (400 nm) Short λ Low f High f Low energy High energy Sub red Feel not see Infrared (IR) Ultraviolet Beyond (UV) violet

33 Electromagnetic (EM) Spectrum Visible ROY G. BIV Long λ (700 nm) (400 nm) Short λ Low f High f Low energy High energy <5% of universe Part of the above from

34 Electromagnetic (EM) Waves Radar TV FM AM

35 Hotter source Higher energy Shorter Higher f EM spectrum V I B G. Y O R Cooler source Lower energy Longer Lower f Radar TV FM AM Hot source?, E?,?, f?

λ is a distance, so its units are m, cm, or mm, etc.

λ is a distance, so its units are m, cm, or mm, etc. Electromagnetic Radiation (How we get most of our information about the cosmos) Radiation travels as waves. Waves carry information and energy. Properties of a wave Examples of electromagnetic radiation: