A ping-pong ball covered with a conducting graphite coating has a mass of 5.1 × 10−³ kg and a charge of 3.3 µC.What electric field directed upward will exactly balance the weight of the ball? (g = 9.8 m/s²)

Question

Quizplus · Accepted Answer

The force on the ball is given by F = mg, where m is the mass of the ball and g is the acceleration due to gravity. 
In order to balance this force with an electrical force, we need to find the electric field E required for the ball to experience a force of F = qE, where q is the charge on the ball. 
E = F/q = mg/q = (5.1 × 10-S11 kg)(9.8 m/s2)/(3.3 × 10-6 C) = 1.5 × 10^14 N/C. 
Therefore, the correct choice is B.

A Ping-Pong Ball Covered with a Conducting Graphite Coating Has