A spherical mirror and a thin spherical lens have each a focal length of –15cm. The mirror and the lens are likely to be

(a) both concave.

(b) both convex.



(a) both concave.



For mirror, 

Concave mirror has its focus on the left.

So, focal length of concave mirror is negative


For lens,

We take focal length of concave lens as negative


Thus, focal length of both Concave mirror and Concave Lens is negative

  1. Class 10
  2. Chapter 10 Class 10 - Light - Reflection and Refraction (Term 1)

About the Author

CA Maninder Singh's photo - Founder at Teachoo
CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 11 years and a teacher from the past 11 years. He teaches Science, Accounts and English at Teachoo