It dosen't drop to zero. It is worse than for fat wires -- but the maths is easier. It's intutively obvious that fat wires should shield better (there's just m

It dosen't drop to zero. It is worse than for fat wires -- but the maths is easier. It's intutively obvious that fat wires should shield better (there's just more shielding). But the original author is right that it the explanation of why this works is lacking from the Feynman point-like appraoch.