# Charge density of a cylindrical shell

Suppose that there are an infinitely long straight current-carrying wire and a thin cylindrical shell enveloping it. The linear charge density of the current-carrying wire is $$-3.6 \text{ nC/m},$$ and the radius of the cylindrical shell is $$1.5 \text{ cm}$$. If the shell has a certain positive surface charge density $$d$$ such that the net electric field intensity of the outside of the shell is zero, what is the value of $$d?$$

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