current density

An electric field of $0.01 \mathrm{~V} / \mathrm{m}$ is applied along the length of a copper wire of circular crosssection with diameter 1 mm . Copper has a conductivity of $5.8 \t...

An infinitely long uniform solid wire of radius a carries a uniform dc current of density $$\widehat{\mathrm j}$$ The magnetic field at a distance r from the center of the wire is...

The electron concentration in a sample of uniformly doped n-type silicon at 300 o K varies linearly from $$10^{17}/cm^3$$ at x = 0 to $$6\times10^{16}/cm^3$$ at x = 2 $$\mu m$$. As...

The unit of $$\nabla\times\mathrm H$$ is