Question

8 four point charge of + ${10}^{-7}C,-{10}^{-7},C,-2\times {10}^{-7}$C and + $2\times {10}^{-7}$ are placed respectively at the corner A, B,C, of a 0.05 m square. Find the magnitude of the resultant force on the charge at D.

• A. 0.2 dyne
• B. 0.2 newton
• C. 2 dyne
• D. 0.02 newton

Answer 1

The correct option is D 0.02 newton

$8$ four point charges of

Four charges are placed at corners of square at side length $O$, $0.5m$ and a charge is placed at centre $\left(O\right)$ of square as shown in the fig.

Forces of repulsion on $1\mu C$ charges at $O$ due to $2\times {10}^{-7}C$ charge at $A$ and $C$ are equal and opposite directions.

$F_{C0}=F_{A0}=\frac{K({10}^{-7}\times 2\times {10}^{-7})}{{\left(\sqrt{{0.05}^2+{0.05}^2}\right)}^2}=0.02N$

Therefore force are cancel to each other.