Define focal length .
Dear Student
Focal length of a lens is the distance between centre of lens and focal point . Focal point is a point on principal axis , at which light rays parallel to principal axis meet after refraction through lens or seem to meet after refraction.
Regards
Focal length of a lens is the distance between centre of lens and focal point . Focal point is a point on principal axis , at which light rays parallel to principal axis meet after refraction through lens or seem to meet after refraction.
Regards