# Notes On Light And Spectra

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Light and Spectra
GEOS 105 – Astronomy with Lab

Pre-Lab Assignment
Print this out, complete it, and get it checked as you arrive in your lab section.

NAME: _____________________________

GEOS 105 Section ____

In Discovering the Essential Universe read Blackbody Radiation, Identifying the Elements…, and
Atoms and Spectra (pages 73-85; Sections 3-12, 3-13, 3-14, 3-15, 3-16, 3-17, and 3-18)
1.

What is the numerical value of the speed of light?

2. How long does it take light to travel from the Sun to the Earth, a distance of 1.50 x 108 km?

3. Light can be described as a wave which has a certain wavelength and frequency. In the sketch below, label the wavelength and define wavelength and frequency.
a.

Wavelength

b. Frequency

c.

Does the speed of light depend on either wavelength or frequency?

Geoscience, Winona State Univ.

Light & Spectra
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Below you will find a spectrum of visible light. What color is the light…
4.

With the longest wavelength?

5.

With the shortest wavelength?

6.

With the highest frequency?

7.

With the lowest frequency?

8.

With the most energy?

9.

With the least energy?

To the right is a sketch of electrons surrounding the nucleus of an atom.
10. Label the nucleus, the electrons, and the electron orbitals.
11. When a photon is absorbed by an atom, what happens to one of the electrons? Draw this on the sketch.

12. When a photon is emitted by an atom, what has happened to one of the electrons? Draw this on the sketch.

13. To the left are three different types of spectra. Identify which spectrum is shown. Your choices are Emission Spectrum,
Absorption Spectrum, and Continuous Spectrum.
a.

b.

c.

Geoscience, Winona State Univ.

Light & Spectra
Page 2 of 9

Light & Spectra
GEOS 105 – Astronomy with Lab
Assign group roles as usual, making sure each person’s role is different than the previous week.
Recorder ____________________

Reporter ____________________
Skeptic ___________________________

Spectroscopy
Tremendously large telescopes are used in astronomy to collect as much light as possible from very distant objects and their invention changed the way we were able to understand and view our
Universe. However, most objects are so far away from Earth that, even with the largest telescopes, they still appear only as points of light. Luckily, light carries a lot of information about any given object throughout the Universe and so we are able to study light and figure out things like what an object is made of, how fast it is moving, how far away it is and how hot it is. Light is amazing!! The instrument that we use to “read” all the information that light carries is called a spectroscope and the science is called spectroscopy. In this lab, you will use a spectroscope to explore many different light sources and you will learn about how we can tell what an object is made of by looking at the light that it emits (or absorbs).

Geoscience, Winona State Univ.

52 meters

28 meters
8

40 meters

52 meters