JEE Main & Advanced Physics Simple Harmonic Motion Question Bank Critical Thinking

  • question_answer
    The amplitude of a damped oscillator becomes half in one minute. The amplitude after 3 minute will be \[\frac{1}{X}\]times the original, where X is                                         [CPMT 1989; DPMT 2002]

    A)            \[2\times 3\]                        

    B)            \[{{2}^{3}}\]

    C)            \[{{3}^{2}}\]                         

    D)            \[3\times {{2}^{2}}\]

    Correct Answer: B

    Solution :

                       Amplitude of damped oscillator                    \[A={{A}_{0}}{{e}^{-\lambda t}};\ \lambda \ =\]constant, t = time                    For t =1 min. \[\frac{{{A}_{0}}}{2}={{A}_{0}}{{e}^{-\lambda t}}\Rightarrow {{e}^{\lambda }}=2\]                    For t = 3 min. \[A={{A}_{0}}{{e}^{-\lambda \times 3}}=\frac{{{A}_{0}}}{{{({{e}^{\lambda }})}^{3}}}=\frac{{{A}_{0}}}{{{2}^{3}}}\]            \[\Rightarrow X={{2}^{3}}\]


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