Question

Choose the correct option.

• A. convex mirror has negative focal lengths concave lens have positive focal length
• B. convex mirror has positive focal length and concave lens have positive focal length
• C. convex mirror has positive focal length and concave lens have negative focal length
• D. both convex mirror and convex lens have negative focal length.

Answer 1

Answer: (C)

1. The focal length of a convex mirror is at the right-hand side of the optical centers, So it is taken as positive.

2. The focal length of the concave lens is at the left-hand side of the lens, hence focal length is negative.

Hence, the convex mirror has positive focal length and the concave lens has a negative focal length.

Thus option C is correct.