Q.A person uses spectacles of 'number' 2.00 for reading. Determine the range of magnifying power (angular magnification) possible. It is a concavo-convex lens (n = 1.5) having curvature of one of its surfaces to be 10 cm. Estimate that of the other.

Apparent size depends on the VISUAL ANGLE an object subtends at the eye, not on its actual size alone -- a nearby small object can look bigger than a distant huge one. MAGNIFYING POWER (angular magnification) of an optical instrument is the ratio of the visual angle $\beta$ of the image it forms to the visual angle $\alpha$ the SAME object would subtend if placed at the eye's LEAST DISTANCE OF DISTINCT VISION, $D=25$ cm (for a telescope, $\alpha$ is instead the angle from the object's own actual position, since it can never be brought closer). This is fundamentally DIFFERENT from LINEAR (lateral) magnification $m=v/u$, which compares image size to object size directly and can, for a simple microscope, be made arbitrarily large even while the angular magnifying power stays modest and bounded. …