Which of the following lenses would you prefer to use while reading small letters found in a dictionary?

(a) A convex lens of focal length 50 cm.

(b) A concave lens of focal length 50 cm.

(c) A convex lens of focal length 5 cm.

(d) A concave lens of focal length 5 cm.

 

Answer

Answer is (c) A convex lens of focal length 5 cm.

 

Explanation 

A concave lens will always give a diminished image.

So, we use a convex lens as it makes an enlarged image

 

Now, the smaller the focal length, the greater will be the power of the lens.

 

Hence, a convex lens of focal length 5cm will be preferable.

  1. Class 10
  2. Chapter 10 Class 10 - Light - Reflection and Refraction

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.