A spherical surface of radius of curvature R, separates air from glass (refractive index = 1.5). The centre of curvature is in the glass medium. A point object 'O' placed in air on the optic axis of the surface, so that its real image is formed at '' inside glass. The line O intersects the spherical surface at P and PO = P. The distance PO equals to: [2025]
(1)

PO = u = –x
P = v = x
PO = P