JEE Main & Advanced Physics Electrostatics & Capacitance Question Bank Self Evaluation Test - Electric Chages and Fields

  • question_answer
    A particle of charge - q and mass m moves in a circle of radius r around an infinitely long line charge of linear charge density \[+\lambda .\]Then time period will be

    A) \[T=2\pi r\sqrt{\frac{m}{2k\lambda q}}\]

    B) \[{{T}^{2}}=\frac{4{{\pi }^{2}}m}{2k\lambda q}{{r}^{3}}\]

    C) \[T=\frac{1}{2\pi r}\sqrt{\frac{2k\lambda q}{m}}\]

    D) \[T=\frac{1}{2\pi r}\sqrt{\frac{m}{2k\lambda q}}\]

    Correct Answer: A

    Solution :

    [a] We have centripetal force equation \[q\left( \frac{2k\lambda }{r} \right)=\frac{m{{v}^{2}}}{r}\text{  so }v=\sqrt{\frac{2kq\lambda }{m}}\] \[\text{Now, }T=\frac{2\pi r}{v}=2\pi r\sqrt{\frac{m}{2kq\lambda }}\text{ where }k=\frac{1}{4\pi {{\varepsilon }_{0}}}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner