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Topic 3: The Spectrocope: New Meanings in Light Science 9 - Space

Isaac Newton passed a beam of sunlight through a glass prism to produce a spectrum of colors

Spectrum: a series of colors formed when a beam of light is separated (by refraction or diffraction) so that its component wavelengths are arranged in order

Spectroscope: a device containing a prism that produces a spectrum In the 1820’s, Joseph von Fraunhofer observed the light from the Sun through a spectroscope. He noticed that the solar spectrum wasn’t a continuous rainbow of all colors, but had dark lines in the rainbow. These dark lines are called spectral lines.

Over the next 50 years, scientists Gustav Kirchoff, and Robert Bunsen studied the light emitted by heating samples of the elements. The Scientists found that each heated element gave off light that was different from all other elements. Each element had a unique spectrum. The study of spectra is called spectroscopy.

3 Types of Spectra 1.Continuous Spectrum: a heated solid, liquid, or gas that produces ALL colors of light (a complete rainbow)

3 Types of Spectra 2. Emission or Bright Line Spectrum: a heated gas sample that emits light of only certain colors

3 Types of Spectra 3. Absorption or Black Line Spectrum: A heated solid, liquid, or gas passes through a cool gas sample which produces light The cool gas absorbs certain colors leaving dark bands

Why would we study different elements spectrums? Looking at the spectrums has helped scientists to identify unknown substances based on the unique spectrum of each element. Each star is made up of different elements – Therefore we use a spectroscope to help us decide what element each star is made up of.

Doppler Shift Effect of motion on length of wavelength Ex: siren of an ambulance

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1.Sound moving away from observer – Long wavelength, low frequency (decrease sound) 2.Sound moving towards observer – Shorter wavelength, high frequency (increase sound)

Movement of Stars Red shift: – moving towards lower frequency – Occurs when stars are moving away – Proves “Big Bang Theory” Blue shift: – Moving towards higher frequency – Occurs when stars are moving closer Note: You must look at the spectrum provided to decide which way to shift!

To do: Analyzing Spectral Patterns WS