JEE Main & Advanced Physics Ray Optics Question Bank Microscope and Telescope

  • question_answer
    The focal lengths of the objective and the eye-piece of a compound microscope are 2.0 cm and 3.0 cm respectively. The distance between the objective and the eye-piece is 15.0 cm. The final image formed by the eye-piece is at infinity. The two lenses are thin. The distances in cm of the object and the image produced by the objective measured from the objective lens are respectively [IIT 1995]

    A)            2.4 and 12.0                          

    B)            2.4 and 15.0

    C)            2.3 and 12.0                          

    D)            2.3 and 3.0

    Correct Answer: A

    Solution :

                       When final image is formed at infinity, length of the tube \[={{v}_{o}}+{{f}_{e}}\] \[\Rightarrow 15={{v}_{o}}+3\]\[\Rightarrow {{v}_{o}}=12\ cm\] For objective lens \[\frac{1}{{{f}_{o}}}=\frac{1}{{{v}_{o}}}-\frac{1}{{{u}_{o}}}\] \[\Rightarrow \frac{1}{(+2)}=\frac{1}{(+12)}-\frac{1}{{{u}_{o}}}\]\[\Rightarrow {{u}_{o}}=-\,2.4\,cm\]


You need to login to perform this action.
You will be redirected in 3 sec spinner