• In an electricity experiment, an electrically charged plastic ball (mass = 100 g) is suspended on a 60 cm long string. When a charged rod is brought near the ball, the rod exerts a horizontal electrical force F_elec on it, causing the ball to swing out to a 20 degree angle and remain at rest there.
• What is the magnitude of the electric force F_elec?
• What is the tension in the string?