Electromagnetic Spectrum
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Transcript of Electromagnetic Spectrum
Electromagnetic Spectrum
Astronomy Chapter 3.1Pages 94, 95, 99 & 100
• Travel in the form of waves
• These waves can travel through empty space.
Electromagnetic Radiation
• ER waves travel at the speed of light– 300,000km per second
• Wavelength, the length from one wave to another, determines the type of radiation
Electromagnetic Spectrum
D. Gamma Rays
B. Visible
C. Ultraviolet
A. Radio Waves
Which of the following has the longest wavelength?
• Emits electromagnetic radiation of all types.
The Sun
Electromagnetic Spectrum• The various types of ER waves arranged on a continuum
• A form of electromagnetic radiation (EMR) that you can see
• A form of energy that travels in waves like:• Radio waves• X-rays• Visible light
What is Visible Light?
• Visible Light– Made of various colors, each with a different
wavelength
– These are the colors seen in a rainbow.
Spectrum
F. Violet
C. Yellow
D. Green
A. Red
Which color has the shortest wavelength?
B. Orange
E. Blue
–When white light is passed through a prism, the light is bent into the visible spectrum.
Spectrum (Prisms)
R – O – Y – G – B – I – V• (Red, Orange, Yellow, Green, Blue,
Indigo, Violet)
Spectrum
Spectroscope• Uses a prism to split the light gathered by a telescope into a spectrum.
• Three different typesContinuous Spectrum
Emission Spectrum
Absorption Spectrum
Three types of Spectra
• Unbroken band of colors
• Shows that the source is emitting all visible wavelengths.
Continuous Spectrum
• A series of unevenly spaced lines of different colors and brightness.
• The bright lines show that the source is emitting light of certain wavelengths.
Emissions Spectrum
• Produced by glowing gases
• Every element has a unique emission spectrum– Allows scientists to determine the elements in
objects.
Emissions Spectrum
• A continuous spectrum crossed by dark lines
• Lines form when light from a glowing object passes through a cooler gas.– The gas absorbs the wavelengths that are
missing.
Absorption Spectrum
• The colors absorbed are the same that the gas would emit– Absorption Spectrum for Hydrogen
– Emission Spectrum for Hydrogen
Absorption Spectrum
D. Absorption Spectrum
B. Emission Spectrum
C. Continuous Spectrum
A. Visible
Which spectrum would you expect to see produced by
glowing gasses?
Which spectrum would you expect to see if you were studying the
gasses on another planet?
D. Absorption Spectrum
B. Emission Spectrum
C. Continuous Spectrum
A. Visible
How do these spectrum allow astronomers to figure out what elements make up the atmospheres of stars and planets?
Absorption Spectrum
• Chemical elements in a star’s atmosphere absorb light from the star.
• Each element absorbs a different wavelength. Each absorbed wavelength is shown as a dark line on a spectrum.
Chemical Composition
• It acts like a finger print each element has a unique set of lines.
• By comparing the star’s spectrum to the known spectrums of different elements, astronomers can determine the elements present.
Chemical Composition
• Most stars have a chemical composition similar to the sun. 73% H, 25%He and 2% other elements.
• Stars at different temps produce different line spectrums.
• If the star is at about 10,000˚C it produces a very strong spectral lines for H.
• If the hydrogen line is not strong, it means the star is cooler than 10,000˚C
Temperatures
Hydrogen
Helium
Sodium
Calcium
Star A
Absorption Spectrums
Hydrogen
Helium
Sodium
Calcium
Star B
Absorption Spectrums
Hydrogen
Helium
Sodium
Calcium
Star C
Absorption Spectrums
Constellations• Patterns of stars in the sky• ORION- The Hunter