Question

Three equal charges are placed on the three corners of a square. If the force between $q_{1}$ and $q_{2}$is $F_{12}$ and that between $q_{1}$and $q_{3}$ is $F_{13}$, the ratio of magnitudes $\frac{F_{12}}{F_{13}}$ is

• A. $1/2$
• B. 2
• C. $1/\sqrt{2}$
• D. $\sqrt{2}$

Answer 1

Answer: (B)

2

Answer 2

$F_{12} = \frac{1}{4\pi\varepsilon_{0}} \cdot \frac{q^{2}}{a^{2}}$ and $F_{13} = \frac{1}{4\pi\varepsilon_{0}} \cdot \frac{q^{2}}{(a\sqrt{2})^{2}}$⇒ $\frac{F_{12}}{F_{13}} = 2$