One plate of a capacitor is charged through a single connecting wire

PHYSICS · Multi-part · Fermi University Physics · Electricity, Magnetism & Electromagnetism · Electric current and circuits · Electric current and circuits

Electricity, Magnetism and Electromagnetism, Ch Current, current density, conductivity and Ohm's law

Problem

One plate of a capacitor is charged through a single connecting wire. A steady current of 3.0 A3.0\,\mathrm{A} flows along the wire into the plate, and no current leaves the plate anywhere else (the gap between the plates is a vacuum and carries no charge across it). Imagine a closed surface SS that encloses the whole plate and cuts the connecting wire once; the outward normal is taken on SS as usual. The plate carries no charge at t=0t = 0. ((a)) What is the outward flux ∮SJ⋅dA\oint_S \mathbf{J}\cdot d\mathbf{A}? ((b)) At what rate does the charge enclosed by SS change? ((c)) How much charge is on the plate after 4.0 ms4.0\,\mathrm{ms}?

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