Question

The power of a lens is defined as the:

Options

• Reciprocal of its focal length

• Sum of its focal length and aperture

• Square of its focal length

• Product of its focal length and refractive index

Answer 1

The power (P) of a thin lens is equal to the reciprocal of its focal length (f) measured in metres, and it is represented by the letter P. This relation shows that a short focal length corresponds to a strong lens.