A straight, cylindrical wire lying along the x axis has a length of 0.510 m and

Question

A straight, cylindrical wire lying along the x axis has a length of 0.510 m and a diameter of 0.205 mm. It is made of a material described by Ohm's law with a resistivity of = 4.00 10-8 · m. Assume a potential of 4.00 V is maintained at the left end of the wire at x = 0. Also assume V = 0 at x = 0.510 m.

(a) Find the magnitude and direction of the electric field in the wire.

magnitude ____V/m ?

direction?

(b) Find the resistance of the wire. ____?

(c) Find the magnitude and direction of the electric current in the wire.

magnitude____ A ?

direction?

(d) Find the current density in the wire.____ MA/m2?

Explanation / Answer

Resistance = rho*length/area = 4*10^-8*0.51/*pi*(0.000205/2)^2 =1.94 ohms
Current = voltage/resistance = 4/1.94 = 2.06 amps (flowing from x=0 to x=0.51m)
Current density = current/area(mm) = 2.06 /pi*(0.000205/2)^2 = 196 MA/m2

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