What is Prism?
Prism is uniform transparent refracting medium bounded by two plane surfaces inclined at an angle.
What is an optical centre?
A point on the principal axis, through which, light rays pass on undefeated, is called the optical centre of the lens.
What is the power of a lens?
Power of a lens is the reciprocal if it's focal length.
What is the unit of power of a lens?
Dioptre(D).