Three charges $-q,+q$ and $+q$ are situated in $X-Y$ plane at points $(0,-a),(0,0)$ and $(0, a)$…
Three charges $-q,+q$ and $+q$ are situated in $X-Y$ plane at points $(0,-a),(0,0)$ and $(0, a)$ respectively. The potential at a point distant $\mathrm{r}(r$ $>a$ ) in a direction making an angle $\theta$ from $Y$ -axis will be
$\frac{\mathrm{K} q}{r}\left(1-\frac{2 a \cos \theta}{r}\right)$
$\frac{2 \mathrm{k} q \cos \theta}{r^{2}}$
$\frac{\mathrm{K} q}{r}$
$\frac{\mathrm{K} q}{r}\left(1+\frac{2 a \cos \theta}{r}\right)$
Solution
$V=\frac{\mathrm{K} q \cdot 2 a \cos \theta}{r^{2}}+\frac{\mathrm{K} q}{r}=\frac{\mathrm{K} q}{r}\left[\frac{2 a \cos \theta}{r}+1\right.$]
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