Question

Define the following terms related to spherical lenses:

(i) Optical center (ii) Centres of s (iii) Principal axis

(iv) Principal focus (v) Focal length​

Answer 1

Answer:

(a) (i) Optical center is defined as the point on the lens which is on the principal axis and the light ray doesn't deflect when passes through it. 

(ii) Centre of curvature is defined as the center of the surface of sphere of which the lens is a part. Since, a lens has two surfaces, so the lens has two centers of curvatures. 

(iii) Principal axis is defined as the straight lines passing through center of curvature. 

(v) Principal focus is defined as the point where beam of light parallel to principal axis, either converges or diverges after refraction.

(vi) Focal length is defined as the distance between the optical center and principal focus of the lens. 

hope this helps

Answer 2

Answer:

1. Optical centre:It is the central point of the lens optical centre is represented by O. When a Ray of light passes through the optical centre the Ray of light does not suffer any dimension and goes straight.
2. Centre of curvature: The centre of spear of which a part of lens is formed is called the centre of curvature of the lens.
3. Principal axis:The line passing through the optical centre of the length and perpendicular to the both faces of the lens is known as the principal axis.
4. principal focus the point at which area after refraction of reflection converges in a convex lens and mirror respectively is known as the principal focus

or

the point at which an independent day after refraction and reflection appears to diverge on the principal axis in a concave lens and concave mirror is known as principal focus

5. Focal length:The distance between the optical centre and principal focus of the lens is known as the focal length.