https://www.youtube.com/watch?v=n_KyYFYNvpI

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

• http://www.youtube.com/watch?v=Kg9F5pN5tlI

• http://www.youtube.com/watch?v=Y5KaeCZ_AaY

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