AMU Medical AMU Solved Paper-1998

  • question_answer
    A magnet makes 30 vibrations per minute at a place, How many vibrations will it make per minute if it is remagnetized so that its pole strength is doubled

    A)  \[\sqrt{{}}600\]              

    B)  \[\sqrt{{}}1200\]

    C)  \[\sqrt{{}}1800\]            

    D)  \[\sqrt{{}}445\]

    Correct Answer: C

    Solution :

    : \[T=2\pi \sqrt{\frac{I}{MH}}=2\pi \sqrt{\frac{I}{LmH}}\] where \[M=Lm\] \[\frac{{{T}_{2}}}{{{T}_{1}}}=\sqrt{\frac{{{m}_{1}}}{{{m}_{2}}}}=\sqrt{\frac{{{m}_{1}}}{2{{m}_{1}}}}=\frac{1}{\sqrt{2}}\] \[\therefore \] \[{{T}_{2}}=\frac{{{T}_{1}}}{\sqrt{2}}\] We know that frequency \[f=\frac{1}{T}\] or \[{{f}_{2}}=\sqrt{2}{{f}_{1}}=\sqrt{2}\times 30=\sqrt{2\times 900}=\sqrt{1800}\]


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