how to draw a ray diagram

If you are sitting Credit Standard Grade or Intermediate 2 you should be able to draw a ray diagram for a convex lens.

At Standard Grade you must be able to draw this diagram for a magnifying glass.  A video for this will be posted shortly.

Intermediate 2 candidates may be asked to draw the diagram for an object placed

  • closer than one focal length
  • between one and two focal lengths
  • more than two focal lengths

from the convex lens.  I will post a video showing each of these three situations.

Let’s start with an introduction to drawing ray diagrams.  This video looks at an object between one and two focal lengths from the lens.  It will show you how to draw the diagram and explain the terms we use to describe the image.

how to draw a ray diagram from mr mackenzie on Vimeo.

Disclaimer: No rabbits were harmed in the making of this video.

bad particle physics

The Large Hadron Collider never seems to be out of the news for long, so it makes sense for someone to provide something for non-physicists to help them understand some of the language of particle physics.

Well done to Reuters, who published a short article called Factbox: Glossary of particle physics terms last week.  Unfortunately, it’s not entirely correct. Follow the link above and use your knowledge of particle physics from unit 2 of the AH Physics course to correct the errors.  It’s always possible that Reuters might pull the article due to the errors so I have attached a pdf of the page below, no excuses!

Thanks to Zapperz for his original post about the article.

total internal reflection

By coincidence (pardon the pun!), both Int2 and S3 have reached the stage of investigating total internal reflection at the same time.  Here is a photo showing total internal reflection of a laser beam in a tank of water.

I’ve put together a short video showing total internal reflection in a semicircular block and a perspex model of an optical fibre.

total internal reflection from mr mackenzie on Vimeo.