Understanding Convex and Concave Lenses

The video tutorial explains the structures and actions of convex and concave lenses. It describes the shape and function of a convex lens, which converges parallel rays to a principal focus, and defines the focal length. It then covers the concave lens, which diverges parallel rays, and explains how to determine its principal focus and focal length.

What is the shape of a convex lens?

• Thicker at the edges than in the middle

• Thicker in the middle than at the edges

• Flat on both sides

• Curved on one side only

What happens to parallel rays when they pass through a convex lens?

• They reflect back

• They converge to a point

• They remain parallel

• They diverge

How does a concave lens affect parallel rays?

• It absorbs them

• It converges them to a point

• It makes them diverge

• It reflects them

Where is the principal focus of a concave lens located?

• At the edge of the lens

• At the point from which rays appear to diverge

• At the point where rays converge

• At the center of the lens

What is the focal length of a lens?

• The distance between the principal focus and the center of the lens

• The distance between the lens and the object

• The distance between the lens and the image

• The distance between the edges of the lens