Question Detail
Question
An electrostatic paint has a 200mm diameter metal sphere at a potential of 25KV that repels paint droplets onto a grounded object. What charge is on the sphere?
Correct Answer
Option C is the correct answer.
Detailed Explanation
Q = CV = (4πε₀r)V = (4π × 8.85×10^-12 × 0.1) × 25,000 = 2.78×10^-7 C = 0.278μC.
Hint
Capacitance of a sphere is C = 4πε₀r.