Question

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

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

Answer 1

Answer: (D)

3.12 N

Answer 2

The situation is shown in figure. Force on $C$ due to $A$ $F_{A C} =\frac{1}{4 \pi \varepsilon_{0}} \frac{q_{A} q_{C}}{r_{A C}^{2}}$ $=\frac{9 \times 10^{9} \times 1 \times 2 \times 10^{-12}}{(0.1)^{2}}=1.8 \,N$ Similarly, $F_{B C}=1.8\, N$ Hence, net force on $C=F_{A C}+F_{B C}=3.6\, N$