Medium MCQ +4 / -1 PYQ · JEE Mains 2020

An electric dipole of moment
$$\overrightarrow p = \left( { - \widehat i - 3\widehat j + 2\widehat k} \right) \times {10^{ - 29}} $$ C.m is
at the origin (0, 0, 0). The electric field due to this dipole at
$\overrightarrow r = + \widehat i + 3\widehat j + 5\widehat k$ (note that $\overrightarrow r .\overrightarrow p = 0$ ) is parallel to :

  1. A $\left( { + \widehat i + 3\widehat j - 2\widehat k} \right)$ Correct answer
  2. B $\left( { + \widehat i - 3\widehat j - 2\widehat k} \right)$
  3. C $\left( { - \widehat i + 3\widehat j - 2\widehat k} \right)$
  4. D $\left( { - \widehat i - 3\widehat j + 2\widehat k} \right)$

Solution

Since $\overrightarrow r$ and $\overrightarrow p$ are perpendicular to each other therefore point lies on the equitorial plane. Therefore electric field at the point will be antiparallel to the dipole moment. <br><br>$\therefore$ $\overrightarrow E || - \overrightarrow p$ <br><br>$\Rightarrow$ $\overrightarrow E ||\left( {\widehat i + 3\widehat j - 2\widehat k} \right)$

About this question

Subject: Physics · Chapter: Electrostatics · Topic: Coulomb's Law

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