Question #22336

1 Answer

General rules for ray diagrams
Always draw a normal line at the point of interaction (reflection or refraction). The normal line should be 90° to the surface / boundary between media.
All angles are measured from the normal line.

Here are some rules for ray diagrams with lenses :

converging lens

1) as object moves toward the focal point:

  • image gets bigger
  • image gets further away on the other side of the lens
  • image is always real and inverted

2) at focal point, no image

3) if object between focal point and lens --

  • image is always bigger than object
  • BUT as the object moves closer to the lens, the image gets smaller
  • image is always virtual and upright

diverging lens

  • image always smaller than object
  • as object moves closer to the lens, image gets bigger (but still smaller than the object)
  • image always on the same side as the object

Rules for concave and convex mirrors are similar with some variation.