NCERT Question 16 - Chapter 10 Class 10 - Light - Reflection and Refraction

Last updated at August 17, 2026 by

Find the focal length of a lens of power – 2.0 D. What type of lens is this?

 

Answer

Given

Power of lens = –2.0 D

 

We know that,

Power of the lens = 1/Focal length

–2 = 1/Focal Length

Focal length = 1/(–2)

Focal length = –0.5 m


Since the focal length is negative, the lens is a concave lens.

 

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