Overloaded plugs and infrared images: Pre-class overheads (November 18 – 22)

(This post is part of an ongoing, semester long series. Each week, as a lecture TA in Physics 100, I choose a pre-class overhead for each of the two lectures I help out in. I attempt to choose images that connect to the current material and that are fun and possibly provocative. Here, I keep a record of the images I choose and thoughts I have about the in-class outcomes.)

As the semester winds down, Physics 100 is finishing up its last few topics. This week, we completed our study of circuits with a discussion of household circuits before moving on to radiation. For the Tuesday iteration of the class, the instructor and I independently had the idea of using the pre-class image of an overloaded plug, like the one in National Lampoon’s Christmas Vacation. The instructor put up a similar image to the one linked there, with the question, “Is this a good idea?”


For the Thursday class, we used a pair of images of the same person taken with a regular visible light camera and an infrared camera. It was interesting to find this picture, because I am quite sure that I have seen it before at some point, perhaps in a course. These pictures led quite naturally into the lecture, because after finishing some content from the previous lecture, the instructor brought out an infrared camera for a fun demonstration. In addition to other ‘experiments’, by using the infrared camera on a student with glasses in the audience, the instructor showed the neat fact that eyeglasses looks like sunglasses in an infrared image.

Comment/question starters

Some possible comment starters for you:

  • A good non-obvious circuit related image would be …
  • I’ve seen that particular infrared picture before also! It was way back, in …
  • I would have used the infrared and visible light pictures much differently! Instead of the above, I would have ….
  • A way you can use pre-class overheads more effectively could be ….
  • What is your goal with the pre-class overheads?
  • The main goal of pre-class overheads should be _____________. To accomplish this, you should …

(Human-Infrared attribution: By NASA/IPAC [Public domain], via Wikimedia Commons; Human-Visible attribution: By NASA/IPAC [Public domain], via Wikimedia Commons.)


One comment

  1. A note for the future: A fun infrared radiation related clip from the Simpsons comes from the “Homer Badman” episode: http://www.youtube.com/watch?v=zmwlXtdX_MQ

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