JEE Main & Advanced Physics Magnetism Question Bank Magnetic Equipments

  • question_answer A bar magnet is oscillating in the Earth?s magnetic field with a period T. What happens to its period and motion if its mass is quadrupled                                                [CBSE PMT 2003]

    A)            Motion remains S.H.M. with time period = 2T

    B)            Motion remains S.H.M. with time period = 4T

    C)            Motion remains S.H.M. and period remains nearly constant

    D)            Motion remains S.H.M. with time period \[=\frac{T}{2}\]

    Correct Answer: A

    Solution :

               As \[T\propto \sqrt{I}\]; where I = moment of inertia \[=\frac{\text{w}{{L}^{2}}}{12}\Rightarrow T\propto \sqrt{\text{w}}\] (w = Mass of magnet. If \[\text{w}\to \]quadrupled, then \[T\to \]doubled i.e. \[{{T}^{'}}=2T\]

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