Question

(a) Define the following terms:
(i) Power of a lens
(ii) Principal focus of a concave mirror​

Answer 1

Answer:

1. The power of a lens is defined as the reciprocal of its focal length in meters, or D = 1/f, where D is the power in diopters and f is the focal length in meters. Lens surface power can be found with the index of refraction and radius of curvature.

2. Define the Principal Focus of a Concave Mirror? Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror. This point is known as the principal focus of the concave mirror.

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Answer 2

the ability of a lens to converge or diverge a beam of ray is called as accomodation of a lens .

2:. focal length : the distance between the pole and the principle focus of a spherical mirror.

Explanation:

a beam of light parallel to principle axis either gets converged or diverged after refraction by a lens .