Question

the focal length is a spherical lens is option a m the distance between optical centre and principal focus of the lens be the distance between centre of curvature and optical centre of the lens should see the diameter of the outline lens the radius of the outline of spherical lens​

Answer 1

Correct Question

The focal length is spherical lens is

(a) the distance between optical centre and principal focus of the lens

(b) the distance between centre of curvature and optical centre of lens

(c) the diameter of the outline lens

(d) the radius of the outline spherical lens ​

Answer

Option a) The distance between optical centre and principal focus of the lens

$\rule{200}2$

• The distance between principal focus and optical centre is called focal length, for a lens. For a mirror, the distance between focus and pole is called focal length
• The distance between centre of curvature and optical centre/pole is called radius of the lens/mirror

$\rule{200}2$

Additional Information

Principal Axis :- The line joining pole/optical centre to  the centre of curvature

Aperture :- The distance between the two ends of a mirror/lens.

Focus :- The point where rays parallel and close to the principal axis meet

Centre of curvature :- The centre of the sphere of which mirror/lens is a part