Question

Roshan makes the table below to describe how to draw a ray diagram for a convex lens.

A 2-column table with 3 rows. The first column labeled Ray from Object to Lens has entries draw through the focal point on the same side of the lens as the object, draw parallel with the main axis, draw to the center of the lens. The second column labeled After passing through the lens has entries the ray goes parallel to the main axis, the ray goes away from the main axis as though it came from the focal point near the object, the ray goes straight through and does not bend.

What error did Roshan make?

The ray that goes through the center should bend and go through the focal point on the other side.
The ray that starts out parallel with the main axis should bend toward the axis and go through the focal point on the other side.
The ray that goes parallel to the main axis after passing through the lens should also be parallel from the object to the lens.
The rays in the table describe how rays are drawn for a concave lens rather than for a convex lens.

Answer 1

Option 2.

For a convex (converging) lens a ray that starts out parallel to the main axis is refracted toward the axis and passes through the focal point on the far side of the lens. Roshan’s table incorrectly says that a parallel ray “goes away from the main axis as though it came from the focal point near the object” (that describes a diverging/concave lens). The other two rows (ray through near focal point → emerges parallel, and ray through center → undeviated) are correct.