Physics · Total internal reflection and its applications, magnification, power of a lens, combination of thin lenses in contact

The power of a lens is negative. State whether it is convex or concave?

The power of a lens is negative. State whether it is convex or concave?

  • A. Concave
  • B. Convex
  • C. Both \( A \& B \)
  • D. can't say

Step-by-step solution

The power of a lens is defined as P = 1/f, where f is the focal length. For a concave lens, the focal length is negative by sign convention, hence the power is negative. For a convex lens, the focal length is positive, so the power is positive. Therefore, a negative power indicates a concave lens.
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