Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave...
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Transcript of Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave...
![Page 1: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/1.jpg)
Chapter 3
Radiation
![Page 2: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/2.jpg)
Information from the Skies
Electromagnetic radiation: Transmission of energy through space
Without physical connection through varying electric and magnetic fields
Example: Light
![Page 3: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/3.jpg)
Information from the Skies
Wave motion: Transmits energy without the physical transport of material
![Page 4: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/4.jpg)
Information from the Skies
Example: Water wave
Water just moves up and down
Wave travels and can transmit energy
![Page 5: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/5.jpg)
Information from the Skies
Frequency: Number of wave crests that pass a given point per second
Period: Time between passage of successive crests
Relationship:
Period = 1 / Frequency
![Page 6: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/6.jpg)
Information from the Skies
Wavelength: Distance between successive crests
Velocity: Speed at which crests move
Relationship:
Velocity = Wavelength / Period
![Page 7: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/7.jpg)
3.1 Information from the Skies
Visible spectrum:
![Page 8: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/8.jpg)
Waves in What?
Water waves, sound waves, and so on, travel in a medium (water, air, …)
Electromagnetic waves need no medium
Created by accelerating charged particles
![Page 9: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/9.jpg)
Waves in What?Electromagnetic waves: Oscillating electric and magnetic fields. Changing electric field creates magnetic field, and vice versa.
![Page 10: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/10.jpg)
Waves in What?
What is the wave speed of electromagnetic waves?
c = 3.0 x 108 m/s
This speed is very large, but still finite; it can take light millions or even billions of years to traverse astronomical distances
![Page 11: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/11.jpg)
The Wave Nature of Radiation
Diffraction is purely a wave phenomenon. If light were made of particles, we would see a spot the size of the hole, with no fuzziness.
![Page 12: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/12.jpg)
The Electromagnetic Spectrum
No limit on wavelengths; different ranges have different names
Note opacity of atmosphere
![Page 13: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/13.jpg)
Thermal Radiation
Blackbody spectrum: Radiation emitted by an object depending only on its temperature
![Page 14: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/14.jpg)
Thermal Radiation
Radiation Laws
1. Peak wavelength is inversely proportional to temperature (frequency is directly proportional to temperature)
![Page 15: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/15.jpg)
Thermal Radiation
Radiation Laws
2. Total energy emitted is proportional to fourth power of temperature (note height of curves)
![Page 16: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/16.jpg)
Kelvin Temperature Scale
• All thermal motion ceases at 0 K
• Water freezes at 273 K and boils at 373 K
![Page 17: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/17.jpg)
Doppler Effect
If one is moving toward a source of radiation, the wavelengths seem shorter; if moving away, they seem longer
![Page 18: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/18.jpg)
Doppler Effect
Relationship between frequency and speed:Yuck - Math
![Page 19: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/19.jpg)
Doppler Effect
Depends only on the relative motion of source and observer
![Page 20: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/20.jpg)
Measuring Velocities with the Doppler Effect
Example: For a speed of 30 km/s, the Doppler shift is given by
Yuck – More Math –
Come On Mr. B.
![Page 21: Chapter 3 Radiation. Units of Chapter 3 3.1 Information from the Skies 3.2 Waves in What? The Wave Nature of Radiation 3.3 The Electromagnetic Spectrum.](https://reader036.fdocuments.net/reader036/viewer/2022081514/5697bf9a1a28abf838c924c1/html5/thumbnails/21.jpg)
Measuring Velocities with the Doppler Effect
This may seem small, but it is easily detectable with a radar gun!
Ok – This we
Get !!