(10%) Problem 6: A particular wire has a length of L = 2.61 m and a circular cro

Question

(10%) Problem 6: A particular wire has a length of L = 2.61 m and a circular cross-sectional area of radius r = 0.19 mm. 25% Part (a) I measure the resistance of this wire and find it to be R = 149 . What is the resistivity of the material the wire is made out 0 Grade Summary Deductions Potential 1% 99% tan() acos) Submissions Attempts remaining: 8 cos asinO atan acotan)sinh) coshO tanh cotanh0 Sin cotan % per attempt) detailed view 1% 0 Degrees Radians Submit Hint I give up! Hints: 0% deduction per hint. Hints remaining: 1 Feedback: 0% deduction per feedback. 25% Part (b) What is the conductivity of this wire, in inverse Ohms per meter? 25% Part (c) Give an expression for the current density in the wire if an electric field E is passing through it. Write this in terms of the resistivity and the other variables in the problem 25% Part (d) Calculate the current in the wire, in milliamperes, if the field strength is 5.87 V/m

Explanation / Answer

formula for resistance is

R = rho L/A

rho = RA/ L

=149 (pi ( 0.19* 10^-3)^2/2.61

= 6.47 * 10^-6

(b)

Conductivity, , is defined as the inverse of resistivity:

,= 1/6.47 * 10^-6

= 154453.29 S/m

(c)

J = E/resistivity

= EL/ RA

= EL/R* pi r^2

(D)

I/A= E/ reesistivity

= EL/ RA

I = EL/R

= 5.87(2.61)/149

= 102.82 mA

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