Posted on 18 May 2011 at 13:23h

I was just heading out yesterday evening when I was faced with the scene shown in the photo. The sun was low and shining straight through the glass of our front door. You can clearly see the path of the light reflected by dust particles. So what's so interesting about that? The sun is always drawn as a yellow ball with rays radiating from it, nothing wrong with that until you come to consider rays on the earth and tell students that they are parallel. They don't look parallel even in my photo it looks like the rays are spreading out a bit but that's due to the perspective not the angle of the rays. This is the sort of problem we are always coming up against as physics teachers. How can you get them to believe something when they have seen with  their own eyes that it's not true?

On a similar theme have a look at this.