• $summary_{type}$: concept
• $word_{count}$: 180

A simple microscope (magnifying glass) is a single convex lens producing a virtual, erect, magnified image. Magnifying power: M = 1 + D/f (image at near point) or M = $\frac{D}{f}$ (image at infinity, relaxed eye), where D = 25 cm. A compound microscope uses two convex lenses: a short-focal-length objective (creates real, magnified, inverted intermediate image) and an eyepiece (acts as simple microscope on the intermediate image). Total magnification: M = $\frac{L}{f_o}$(1 + D/$f_e$) at near point, or M = \frac{L}{f_o}$$\frac{D}{f_e} at infinity, where L is the tube length. For maximum magnification, both $f_o$ and $f_e$ should be small while L should be large. The resolving power of a microscope is 2n sinθ/(1.22λ), enhanced by oil immersion (increasing n). JEE problems typically ask for magnification calculations or conceptual questions about the role of each lens.