Observe the following ray diagram and answer the questions given below :[Figure: an object AB placed just beyond the focus Fo of a small convex lens marked “Objective lens”; the real, inverted, magnified image formed by it lies between the objective…

Answer: (a) A compound microscope; (b) the two lenses together give a very large magnification; (c) to see very small objects such as cells and micro-organisms.

(a) The instrument has two convex lenses — an objective of short focal length and an eyepiece — so it is a compound microscope.

(b) The objective forms a real, inverted and magnified image of the object. This image lies within the focal length of the eyepiece, which then forms a virtual, inverted and highly magnified final image. The total magnification is the product of the magnifications of the two lenses, \(M = m_o \times m_e\), so the combined effect is a much greater magnification than either lens alone.

(c) A compound microscope is used to observe very minute objects — cells, bacteria, blood cells and other micro-organisms — in science laboratories and hospitals.