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NEET Sample Paper NEET Sample Test Paper-46

  • question_answer
    Parallel beam of light is incident on the system of two convex lenses of focal length \[{{f}_{1}}=20\] cm and \[{{t}_{2}}=10\] cm. What should be the distance between the two lenses so that rays after refraction from both the lenses pass undeviated-  

    A) 60 cm

    B)                    30 cm

    C)                    90 cm

    D)                    40 cm

    Correct Answer: B

    Solution :

    \[P=0={{P}_{1}}+{{P}_{2}}-d\,{{P}_{1}}\,{{P}_{2}}\] \[\Rightarrow \,\,\,\,\frac{1}{{{f}_{1}}}+\frac{1}{{{f}_{2}}}=\frac{d}{{{f}_{1}}{{f}_{2}}}\] \[\Rightarrow \,\,\,\,\frac{1}{10}+\frac{1}{20}=\frac{d}{10\,\,\times \,\,20}\] \[\Rightarrow \,\,\,\frac{30}{10\,\,\times \,\,20}\,\,=\,\,\frac{d}{10\,\,\times \,\,20}\] \[d\text{ }=\text{ }30\]


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