Group Light Quiz 2

Electromagnetic Spectrum

    1. Label the parts of the wave.
    2. Wavelength

      Amplitude

       

    3. What is one of the units for measuring a wavelength? How many centimeters are in that unit?
    4. List the 6 subdivisions of the Light Spectrum in order, from the longest wavelength to the shortest wavelength.
    5. Yellow

      Violet

      Red

      Orange

      Green

      Blue

    6. Place the 6 subdivisions of the Electromagnetic Spectrum in order, from the longest wavelength to the shortest wavelength.
    7. X-Rays

      Visible light

      Ultraviolet radiation

      Radio waves

      Infrared radiation

      Gamma Rays

    8. Which subdivision of the Electromagnetic Spectrum did we experiment with in the Reflection & Refraction Lab? _______________
    9. Which of the above falls into the Stellar Spectrum? _______________
    10. Which of the above enters Earthís atmosphere? _______________

Most stars are made of Hydrogen. In the coldest stars, hydrogen gas does not get too much energy, so it only shows week spectral lines. In warmer stars, hydrogen gas shows stronger spectral lines. But in the hottest stars, hydrogen gas is ionized, changed, so that the hydrogen gases do not produce spectral lines.

Table 1

Spectral

Class

Color

Approximate Temperature (K)

Principal Features

O

Blue

> 25,000

Lines of ionized helium, nitrogen, and silicon. Hydrogen lines appear only weakly.

B

Blue

11,000-25,000

Lines of neutral helium, silicon, ionized oxygen and magnesium. Hydrogen lines more pronounced than in O-type stars.

A

Blue

7,500-11,000

Strong lines of hydrogen. Also lines of magnesium, silicon, iron, titanium, calcium, and others.

F

Blue to White

6,000-7,500

Hydrogen lines are weaker than in A-type stars, but are still conspicuous. Lines of ionized calcium, iron and chromium.

G

White to Yellow

5,000-6,000

Lines of ionized calcium are the most conspicuous. Lines of ionized and neutral metals. Hydrogen lines are weaker than in F-type stars.

K

Orange to Red

3,500-5,000

Lines of neutral metals are most visible.

M

Red

<3,500

Strong lines of neutral metals and molecular bands of titanium oxide are most visible.

From Abell, George O. 1980. Realm of the Universe, 2nd Ed. Saunders College, pp. 226.

  1. Based upon Table 1 and the above, what three things can a starís Stellar Spectrum tell you? _______________, _______________, _______________.
  2. Based upon the above, what can astronomers learn from a starís Stellar Spectrum?