A lens has a power of +2.5 D. What is the focal length of the lens in meters?

Practice Questions

Q1
A lens has a power of +2.5 D. What is the focal length of the lens in meters?
  1. 0.4 m
  2. 0.5 m
  3. 0.6 m
  4. 0.7 m

Questions & Step-by-Step Solutions

A lens has a power of +2.5 D. What is the focal length of the lens in meters?
  • Step 1: Understand that the power of a lens (P) is related to its focal length (f) by the formula P = 1/f.
  • Step 2: Rearrange the formula to find the focal length: f = 1/P.
  • Step 3: Substitute the given power into the formula: f = 1/2.5.
  • Step 4: Calculate the value: 1 divided by 2.5 equals 0.4.
  • Step 5: Conclude that the focal length of the lens is 0.4 meters.
  • Lens Power and Focal Length – The power of a lens is the reciprocal of its focal length, measured in diopters (D), where P = 1/f.
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