Exam-style question
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What is the relationship between the focal length and the optical power of a lens?.
- A.Optical power is the reciprocal of the focal length in meters.
- B.Optical power is the square of the focal length in meters.
- C.Optical power is directly proportional to the focal length.
- D.Optical power is the product of the focal length and the lens thickness.
Model answer
What a good answer should say
- Optical power is the reciprocal of the focal length in meters.
Explanation
Why this works
The formula for optical power (P) is given by P = 1/f, where f is the focal length in meters. This means that as the focal length decreases, the optical power increases, indicating a direct relationship.
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