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

MCQ

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

#### Options

• both concave

• both convex

• the mirror is concave and the lens is convex

• the mirror is convex, but the lens is concave

#### Solution 1

both concave

By convention, the focal length of a concave mirror and a concave lens are taken as negative. Hence, both the spherical mirror and the thin spherical lens are concave in nature.

#### Solution 2

Both concave

According to the sign convention, the focal length for both a concave mirror and a concave lens is negative.

Concept: Concave Mirror
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#### APPEARS IN

NCERT Class 10 Science
Chapter 10 Light – Reflection and Refraction
Q 4 | Page 185
Lakhmir Singh Class 10 Physics (Science)
Chapter 5 Refraction of Light
Q 29 | Page 247