JEE MAIN - Physics (2020 - 9th January Morning Slot - No. 8)

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 :
$$\left( { + \widehat i + 3\widehat j - 2\widehat k} \right)$$
$$\left( { + \widehat i - 3\widehat j - 2\widehat k} \right)$$
$$\left( { - \widehat i + 3\widehat j - 2\widehat k} \right)$$
$$\left( { - \widehat i - 3\widehat j + 2\widehat k} \right)$$

Explanation

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.

$$ \therefore $$ $$\overrightarrow E || - \overrightarrow p $$

$$ \Rightarrow $$ $$\overrightarrow E ||\left( {\widehat i + 3\widehat j - 2\widehat k} \right)$$

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