Homework #1

Due at start of class on Friday Jan 13. Answers can be hand written or typed. Because this homework has no mathematical or graphical elements, your answers can be sent in the body of an email.

Part 1: Sustainable Energy

Watch the first 6 min 15 seconds of this video of David MacKay's presentation: https://www.youtube.com/watch?v=GFosQtEqzSE

Use the information in the video to answer these questions:

  1. List three reasons that fossil fuels are not sustainable.
  2. Why does MacKay suggest that we sometimes use numbers that are deliberately approximate?
  3. Give at least one reason why kiloWattHours (kWh) are a natural choice of energy unit for conversations about sustainable energy.
  4. How many kWh per day does it take to run a typical north american house?
  5. How many kWh does it take to drive 100 km?

Part 2: Quantum mechanics of electromagnetic radiation and molecular absorption

Watch the whole 5-minute video “How quantum mechanics explains global warming”: https://www.youtube.com/watch?v=-EJOO3xAjTk

Use the information in the video to answer these questions:

  1. Which color of visible light does oxygen gas absorb?
  2. The earth glows strongly in which part of the electromagnetic radiation spectrum?
  3. What is the minimum temperature for a piece of iron to emit in the visible part of the electromagnetic radiation spectrum?
  4. What percentage of electromagnetic radiation emitted by a traditional light bulb is invisible to human eyes?
  5. After a carbon dioxide molecule absorbs an infra-red photon, what direction will a new infra-red photon be emitted from the molecule?