Q.Define and describe magnifying power of an optical instrument. How does it differ from linear or lateral magnification?

[!TLDR] Magnifying power is the ratio of the visual angle the instrument's image makes to the visual angle the object makes at the near point D (or, for telescopes, at its own position) -- an angular comparison, unlike linear magnification which directly compares image-to-object SIZE. [!ANSWER] M = beta/alpha (angul …

Magnifying power (angular magnification) of an optical instrument is defined as the ratio of the visual angle beta subtended at the eye by the image the instrument forms, to the visual angle alpha that the SAME object would subtend if instead viewed directly, placed at the eye's least distance of distinct vision D=25 cm (for a telescope specifically, alpha is instead the angle the object subtends from its own actual position, since a distant astronomical object can never physically be brought any closer to compare against). It captures how much BIGGER something LOOKS to the eye as a result of using the instrument, compared with the best the unaided eye alone could do. …

Define magnifying power as the ratio of visual angles (image vs object-at-D), contrast it explicitly with linear magnification (a size ratio, m=v/u), and use the simple-microscope in …

Conflating magnifying power with linear magnification, or defining magnifying power simply as 'how much bigger the image looks' without the precise angular-ratio (beta/alp …