A charge is added to a small sphere by touching it with a probe that was raised

Question

A charge is added to a small sphere by touching it with a probe that was raised to a 3000 V potential. The spheres used had a diameter of 3.7 cm’s and raised the entire surface to an electric potential of 3000 V’s. Using some reasonable assumptions:

How much charge was collected on the surface of these spheres

What is the force (in Newton’s) between these two spheres when they were 10 cm’s apart.

Assuming one is charged to +3000 V, and the other to -3000V, what would the capacitance be for this arrangement? (explain justifications for any simplifications)

P.S. Please provide a detailed answer. I'm having hard time understading the basic concept behind this problem. Please help. Thank you.

Explanation / Answer

(a) We know that the potential on the surface of the sphere is given by

V = kQ/R = 3000 V

=> Q = 3000 * (3.7/2) * 10-2 / (8.99 * 109) = 6.17 * 10-9 C

(b) The electrostatic force between the two spheres is

F = kQ2/R2 = (8.99 * 109) * (6.17 * 10-9)2 / (10 * 10-2)2 = 3.43*10-5 N

The capacitance is given by

C = Q/V = 6.17*10-9/3000 = 2.053*10-12F = 2.053 pF

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.