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A diverging lens has a negative focal length. What sign does its power then carry?
APositive, since power always stays positive regardless of lens type
BZero, since diverging lenses have no power at all
CIt depends only on the material the lens is made from
DNegative, matching the negative sign of the focal length
Answer & Solution
Correct answer: D. Negative, matching the negative sign of the focal length
1. Power is the reciprocal of focal length, so the two quantities always share the same sign.
2. A diverging lens has a negative focal length, so its power is also negative.
3. A converging lens, with positive focal length, correspondingly has positive power, so power is not always positive regardless of lens type.
_Source: OpenStax Physics (CC BY 4.0), Ch 16 "Mirrors and Lenses", section 16.3 Lenses_
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