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

  • question_answer
    Two identical blocks are kept on a frictionless horizontal table connected by a spring of stiffness k and of original length \[{{l}_{0}}.\] A total charge Q is distributed of spring at equilibrium of equal to x. Value of Q is

    A) \[2{{\ell }_{0}}\sqrt{4\pi {{\varepsilon }_{0}}k\left( {{\ell }_{0}}+x \right)}\]

    B) \[2x\sqrt{4\pi {{\varepsilon }_{0}}k\left( {{\ell }_{0}}+x \right)}\]

    C) \[2\left( {{\ell }_{0}}+x \right)\sqrt{4\pi {{\varepsilon }_{0}}kx}\]

    D) \[\left( {{\ell }_{0}}+x \right)\sqrt{4\pi {{\varepsilon }_{0}}kx}\]

    Correct Answer: C

    Solution :

    [c] For maximum elongation charges on the blocks must be equal to 0/2 on each block. \[\therefore \frac{1}{4\pi {{\varepsilon }_{0}}}\frac{\frac{Q}{2}\frac{Q}{2}}{{{\left( {{\ell }_{0}}+x \right)}^{2}}}=kx\text{    }Q=2\left( {{\ell }_{0}}+x \right)\sqrt{4\pi {{\varepsilon }_{0}}kx}.\]


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