BCECE Engineering BCECE Engineering Solved Paper-2002

  • question_answer
    If in Ramsdens eyepiece, the field lenses have focal lengths \[{{f}_{1}}\] and \[{{f}_{2}}\] respectively and     separated by a distance d then :

    A) \[{{f}_{1}}=3{{f}_{2}}and\,d={{f}_{1}}+{{f}_{2}}\]

    B) \[{{f}_{1}}={{f}_{2}}and\,d=\frac{2}{3}{{f}_{1}}\]

    C) \[{{f}_{1}}=\frac{2}{3}{{f}_{2}}and\,d=\frac{2}{3}{{f}_{1}}\]

    D) \[{{f}_{1}}={{f}_{2}}and\,d={{f}_{1}}+{{f}_{2}}\]

    Correct Answer: B

    Solution :

    Key Idea: Ramsdens eyepiece is oho known as positive eyepiece, Ramsdens eyepiece is an eyepiece consisting of two plano-convex lenses of equal focal length placed with their curved surfaces towards each other, and separated by a distance somewhat less than the focal distance of the nearest eye, the image of the object viewed beyond both lenses. The two lenses are separated by a distance of \[\frac{2f}{3}.\]


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