Question

Choose the correct option.

• A. Convex lens has negative focal length and concave lens has a positive focal length.
• B. Both convex lens and concave lens have a positive focal length.
• C. Convex lens has positive focal length and concave lens has a negative focal length.
• D. Both convex lens and concave lens have a negative focal length.

Answer 1

The correct option is C

Convex lens has positive focal length and concave lens has a negative focal length.

Focus of converging or convex lens is at the right hand side of the lens, hence focal length is positive.

Focus of diverging or concave lens is at the left hand side of the lens, hence focal length is negative.