BITSAT 2021
- Exam
- BITSAT
- Year
- 2021
- Subject
- Physics
- Chapter
- Electrostatics
BITSAT 2021 · Physics · Electrostatics
A charge Q is placed at each of the opposite corners of a square. A...
A charge is placed at each of the opposite corners of a square. A charge is placed at each of the other two corners. If the net electrical force on is zero, then equals:
Options
- A
- B
- C
- D
Correct answer
D.
Step-by-step solution
It is given that Where and are the forces applied by charges placed at and on the charge placed at . \begin{array}{l} \Rightarrow \overrightarrow{\mathrm{F}_{\mathrm{B}}+\overrightarrow{\mathrm{F}_{\mathrm{D}}=-\overrightarrow{\mathrm{F}_{\mathrm{A}} \\ \left|\overrightarrow{\mathrm{F}_{\mathrm{B}}+\overrightarrow{\mathrm{F}_{\mathrm{D}}\right|=\sqrt{2} \frac{\mathrm{KqQ}}{\mathrma^{2}} \\ \Rightarrow\left|\overrightarrow{\mathrm{F}_{\mathrm{A}}\right|=\frac{\mathrm{KQ}^{2}}{2 a^{2}} \\ \therefore \sqrt{2} \frac{\mathrm{KqQ}}{a^{2}}=-\frac{\mathrm{KQ}^{2}}{2 a^{2}} \\ \Rightarrow \frac{\mathrm{Q}}{q}=-2 \sqrt{2} \end{array}