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Draw a ray diagram showing the image formation by a compound microscope. Hence, obtain expression for total magnification when the image is formed at infinity. |
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Answer» SOLUTION :The ray diagram is given in FIG. 9.85. If `m_0` and me be the magnifications produced by the objective lens and eye-lens respectively, then total magnifying power of microscope `m=m_(0) xx m_( e)` If `u_(0)` be the distance of object AB from objective EVE lens and `v_(0)`be the distance of image A.B.formed by objective from itself, then  `m_(0)=-v_(0)/u_(0)` The magnifying power of eyepiece when the final image is formed at infinity (i.e., `u_e -f_e`), is `m_( c) =D/f_(e)` `m_(e) = D/f_(e)` As a first approximation, `u_(0)=f_(0)`and `v_(0)=L` = distance between objective and eyepiece (or LENGTH of microscope tube), then, we have: `m=-L/f_(0).D/f_(e)` To increase the magnifying power of microscope focal LENGTHS of objective as well as eyepiece should be small enough. |
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