Question

I am unable to tackle questions related to ray diagrams. I do know how to do them, but when the question is twisted I am unable to answer. Please help me overcome this problem. I do not know which ray diagram should be drawn as per the question's requirement.

Answer 1

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