MOLECULES and LIGHT
In this activity, you will use a simulator to explore how light interacts with the various molecules found in
the Earth’s atmosphere. Open the simulator from the course website under Week 3 assignments,
Activity 3-1.
When the simulation first comes up, there is a carbon
monoxide molecule (one carbon atom and one oxygen
atom) on the screen and the light is set to infrared.
1. Turn on the light source by clicking and dragging the
slider on the lamp all the way to the right. Watch the CO
molecule for a few seconds. Does it absorb any of the
infrared photons? If so, does it cause the molecule to
vibrate or rotate?
2. Try changing the type of light to microwave. Does the CO molecule absorb any of the microwave
photons? If so, does it cause the molecule to vibrate or rotate?
3. Now, try the other types of light. Does CO absorb visible or ultraviolet photons?
4. Explore how the different wavelengths of light interact with the molecules in the simulation. Record
your observations in the chart below.
Microwave
CO
N2
O2
CO2
H2O
NO2
O3
Infrared
Visible
Ultraviolet
5. What tends to happen to molecules when they absorb microwave photons?
6. What tends to happen to molecules when they absorb infrared photons?
7. What do you notice about the interaction of visible photons and the molecules?
8. What do you notice about the interaction of ultraviolet photons and the molecules?
9. The molecules in this activity are most all present in the Earth’s atmosphere. Explain why visible light
can penetrate the Earth’s atmosphere, but infrared light tends to get absorbed by the atmosphere.
10. Use the internet to research the following three topics. For each topic, write a short summary and
describe how the topic relates to something specific that you observed in this simulator. That is, each
summary should include a discussion about specific molecules and specific ranges of the
electromagnetic spectrum.
Topic #1: How do microwave ovens work?
Topic #2: What is the Greenhouse effect?
Topic #3: Why is the Earth’s ozone (O3) layer important?