Unformatted text preview: design in order to increase its resistance without changing the material you are using? 5. (15 points) A long, round wire of radius a and conductivity σ is coated with a material of conductivity . 1 σ . a) what must be the thickness of the coating so that the resistance per unit length of the total new coated wire is 25% less than the resistance of the uncoated wire% ? b) Assuming a total current I in the coated wire, ﬁnd-→ J and-→ E in the wire. 1...
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- Summer '08
- current density, surface current density, volume current density