Three charges +Q, q, +Q are placed respectively, at distance, 0, frac d2 and d from origin, on x- ax

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1. Electric Charges and Fields

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Three charges $+Q, q, +Q$ are placed respectively, at distance, $0, \frac d2$ and $d$ from the origin, on the $x-$ axis. If the net force experienced by $+Q$, placed at $x = 0$, is zero, then value of $q$ is

A

$-\frac Q2$

B

$+\frac Q2$

C

$+\frac Q4$

D

$-\frac Q4$

(JEE MAIN-2019)

Solution

For equilibrium,

$\vec{F}_{a}+\vec{F}_{B}=0$

$\vec{F}_{a}=-\overrightarrow{F_{B}}$

$\frac{k Q Q}{d^{2}}=-\frac{k Q q}{(d / 2)^{2}}$

$\Rightarrow q=-\frac{Q}{4}$

Standard 12

Physics

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