Electrostatics — Medium JEE physics MCQ
**[JEE Mains 2026]** A simple pendulum with a bob of mass m and charge q is in equilibrium in the presence of a uniform horizontal electric field E. If the thread makes an angle θ with the vertical, what is the tension in the thread?
- A. mg/cosθ
- B. qE/sinθ
- C. √((mg)² + (qE)²)
- D. mg + qE
Solution
At equilibrium: T sinθ = qE and T cosθ = mg.
Squaring and adding: T² = (mg)² + (qE)².
Therefore, T = √((mg)² + (qE)²).