Multiple choice

Which of the following lenses would you prefer to read small letters of dictionary?

  1. A convex lens of focal length 30 cm

  2. A concave lens of focal length 30 cm

  3. A convex lens of focal length 5 cm

  4. A concave lens of focal length 5 cm
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A convex lens of focal length 5 cm is preferred to read small letters of dictionary. To view the small letters in a dictionary, a convex lens of small focal length is suitable. This is because for working as a simple microscope, convex lens of small focal length is needed. The image is formed at the near point (D = 25 cm) for easy viewing.

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