2. Questions Bank
  3. JEE Main & Advanced
  4. Physics
  5. Electrostatics & Capacitance

JEE Main & Advanced Physics Electrostatics & Capacitance Question Bank Electric Dipole

  • question_answer
    Two opposite and equal charges \[4\times {{10}^{-8}}coulomb\] when placed \[2\times {{10}^{-2}}cm\] away, form a dipole. If this dipole is placed in an external electric field \[4\times {{10}^{8}}newton/coulomb\], the value of maximum torque and the work done in rotating it through \[180{}^\circ \] will be                                   [MP PET 1996]

    A)                    \[64\times {{10}^{-4}}Nm\] and \[64\times {{10}^{-4}}J\]

    B)                    \[32\times {{10}^{-4}}\]Nm and \[32\times {{10}^{-4}}J\]

    C)                    \[64\times {{10}^{-4}}Nm\] and \[32\times {{10}^{-4}}J\]

    D)                    \[32\times {{10}^{-4}}Nm\] and \[64\times {{10}^{-4}}J\]

    Correct Answer: D

    Solution :

                       Dipole moment \[p=\text{4}\times \text{1}{{0}^{\text{8}}}~\times \text{2}\times \text{1}{{0}^{\text{4}}}=\text{ 8}\times \text{1}{{0}^{\text{12}}}m\] Maximum torque \[=pE=\text{8}\times \text{1}{{0}^{\text{12}}}\times \text{4}\times \text{1}{{0}^{\text{8}}}\] \[=\text{ 32}\times \text{1}{{0}^{\text{4}}}Nm\] Work done in rotating through \[\text{18}{{0}^{\text{o}}}=\text{ 2}pE\] \[=\text{ 2}\times \text{32}\times \text{1}{{0}^{\text{4}}}=\text{ 64}\times \text{1}{{0}^{\text{4}}}J\]


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