1. Chapter 24 Studying the Sun
Section 1
The Study of Light
Notes 24-1

2. Vocabulary Electromagnetic spectrum Photon Spectroscopy
Continuous spectrum
Absorption spectrum
Emission spectrum
Doppler Effect

3. Electromagnetic Radiation
All different types of wavelengths of energy
Gamma rays to radio waves
Organized in the electromagnetic spectrum
All energy travels at the same speed through a vacuum = 300,000 km per sec

4. Electromagnetic Radiation
Light can behave like a wave or a particle
It has a wavelength and a wave height
Can be separated into separate colors and wavelengths by a prism

5. Electromagnetic Radiation
In some cases, light acts like a stream of particles called photons
Small bullets from a machine gun
They push matter
The force they exert is called radiation pressure
Photons from the sue cause the tail of the comet
Shorter wavelengths have more energetic photons and longer wavelengths have less energy

6. Spectroscopy
Study of the properties of light that depend on wavelength
Sir Isaac Newton used a prism to separate light into its component colors
ROY G BIV
Continuous Spectrum
Made by an incandescent solid, liquid or gas under pressure
Uninterrupted band of color
Comes from an incandescent

7. Spectroscopy Absorption Spectrum
Visible light passes through a cool gas under low pressure
Gas absorbs some wavelengths
Continuous spectrum with dark lines running through it

8. Spectroscopy Emission Spectrum Important
Produced by hot gases under low pressure
Bright lines of particular wavelengths
Important
Each element or compound has a unique set of spectra lines
These lines act as fingerprints
They show which elements or compounds are present in a star

9. Emission Spectrum

10. Spectroscopy Sun’s spectrum Has thousands of dark lines
More than 60 elements have been identified in the sun

12. Doppler Effect
The perceived change in wavelength of a wave that is emitted by source that is moving away or toward an object.
Moving toward an object causes the wavelengths to push together and become shorter
Blue Shift
Moving away from an object causes the wavelengths to spread apart and become longer
Red Shift
Used to determine if a star or bright object is moving away or towards the observer
Amount of shift depends on the rate at which it occurs
Larger the shift; the faster the speed
Smaller the shift; the slower the speed
Compare the absorption spectrum to the standard spectrum produced in a lab

13. Doppler Shift