An isolated metal sphere of radius carries a charge
PHYSICS · Multi-part · Fermi University Physics · Electricity, Magnetism & Electromagnetism · Conductors, capacitance and boundary-value electrostatics · Conductors, capacitance and boundary-value electrostatics
Electricity, Magnetism and Electromagnetism, Ch Conductors, screening and capacitance
Problem
An isolated metal sphere A of radius 6.0cm carries a charge +9.0nC. A second isolated metal sphere B of radius 3.0cm is uncharged and stands far away, at a separation huge compared with both radii, so each sphere may be treated as isolated (the capacitance of an isolated sphere of radius R is 4πε0R, with V=0 at infinity). The two are now joined by a long thin conducting wire of negligible capacitance, and equilibrium is reached in vacuum.
((a)) Find the capacitance of the joined pair.
((b)) Find their common potential.
((c)) Find the charge that ends up on each sphere.
((d)) Find the energy stored in the field after the connection.
((e)) Find the outward electrostatic pressure on the surface of sphere B afterwards.