**Question:**

Charges $-\mathrm{q}$ and $+\mathrm{q}$ located at $\mathrm{A}$ and $\mathrm{B}$, respectively, constitute an electric dipole. Distance $\mathrm{AB}=2 \mathrm{a}, \mathrm{O}$ is the mid point of the dipole and $\mathrm{OP}$ is perpendicular to $\mathrm{AB}$. A charge $\mathrm{Q}$ is placed at $\mathrm{P}$ where $\mathrm{OP}=y$ and $y>>2 \mathrm{a}$. The charge Q experiences an electrostatic force F. If Q is now moved along the equatorial line to $P^{\prime}$ such that $O P^{\prime}$

$=\left(\frac{y}{3}\right)$, the force on $\mathrm{Q}$ will be close to: $\left(\frac{y}{3}>>2 \mathrm{a}\right)$

Correct Option: 4

**Solution:**

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