Q.Compare the working principle of a simple microscope and a compound microscope, and explain why a compound microscope can reach a much higher magnifying power than a simple microscope.

A simple microscope is just one convex lens, used to view an object placed within its focal length so that a single stage of magnification produces an enlarged virtual image; because the magnifying power $M=1+D/f$ grows only by using an ever shorter focal length $f$, and a very short focal length lens suffers increasingly severe optical aberrations, a simple microscope's magnifying power is, in practice, capped at around $10\times$. A compound microscope instead uses two convex lenses in series: a short-focal-length objective forms a real, inverted, and already substantially magnified intermediate image of the tiny object; this intermediate image is then used as the "object" for a second lens, the eyepiece, which — acting exactly like a simple microscope on this already-magnified intermediate image — magnifies it a second time into the final image the eye sees. Because the overall magnifying power is the PRODUCT of the objective's own magnification and the eyepiece's own magnifying power, $M=m_o\times M_e$, and each of the two factors can independently be made reasonably large without e …

Compare the single-lens, single-magnification-stage principle of the simple microscope with the two-lens, two-stage (m …

• Thinking the compound microscope's two lenses simply ADD their magnifications rather than MULTIPLY.
• Describing the eyepiece as forming a real image (it forms a virtual final image, exactly like a simple microscope). …