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What is the position of the object for a simple microscope ? What is the maximum magnification of a simple microscope for a realistic focal length? |
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Answer» Solution :When an object is placed between principal FOCUS and optical centre of a convex lens, a virtual and erect image will be formed on the same side of the object. Magnifying power : It is defined as the RATIO of the angle subtended a the eye by the image to the angle subtended by the object at the eye. `m=(alpha)/(BETA)~=(Tan alpha)/(Tan beta)` From figure `OJ=IJ',angleIO'G= alpha and angleIO'J'=beta` Magnifying power `(m)=(alpha)/(beta)` `=(Tan alpha)/(Tan beta)` for small angles `=("IG/IO'")/("IJ'/IO'")` `m=("IG")/("IJ'")=("IG")/("OJ")=(therefore" IJ' = OJ")` `Delta^("le")"IGO' and "Delta^("le")" OJO' are similar"` `("IG")/("OJ")=("IO'")/("OO'")=(-D)/(-u)` `m=(D)/(u)"...........................................(1)"` The above equation can be written as `m=1+(D)/(f)"..................................(2)"` This shows that smaller the FOCAL length of the lens, greater will be the magnifying power of microscope. 
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