Question #22336
1 Answer
Feb 4, 2015
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.