Question

Three charges $1\mu C$, $1\mu C$ and $2\mu C$ are kept at the vertices A, B and C respestively of an equilateral triangle ABC of $10cm$ side. The resultant force on the charge at the vertex $C$ is :

• A. 0.9 N
• B. 1.8 N
• C. 2.72 N
• D. 3.12 N

Answer 1

The correct option is D 3.12 N

Component of Forces due to $BandAinx$ direction acting on $C$ cancel out each other $\therefore F_x=0$
in $y$ direction forces add up
We get $F_y=\frac{k\left(1\mu C\right)\left(2\mu C\right)}{(10\times {10}^{-2}{)}^2}\times sin60\times 2$

$=\frac{9\times {10}^9\times 1\times {10}^{-6}\times 2\times {10}^{-6}}{100\times {10}^{-4}}\times \frac{\sqrt{3}}{2}\times 2$

$=3\cdot 1176N$