VMMC VMMC Medical Solved Paper-2015

  • question_answer
    A magnifier (lens) has the focal length 4.0 cm. If a small object is placed at a distance 3.6 cm from the magnifier the lens and angular magnifications will respectively be

    A) 10 and 7              

    B) 9 and 6

    C) 3 and 4                 

    D)  4 and 3

    Correct Answer: A

    Solution :

    As, linear magnification \[=\frac{v}{u}\] \[=\frac{-36cm}{-36cm}=10\] Now, when object is placed at a distance \[{{u}_{0}}\] from the lens, then angle subtained by the object on the lens is \[\beta =\frac{h}{{{u}_{0}}},\]where h is the height of the object. Also, the maximum angle subtainded on the unaided eye is \[\alpha =\frac{h}{D}\] Thus, angular magnification, \[m=\frac{\beta }{\alpha }=\frac{D}{{{u}_{0}}}=\frac{25cm}{3.6cm}\approx 7\]


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