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will thumbs up if you answer all parts Problem 3 (7 pts) A wire consists of two

ID: 2032786 • Letter: W

Question

will thumbs up if you answer all parts

Problem 3 (7 pts) A wire consists of two segments of different diameters but made from the same metal of conductivity ?-3x107 m. Segment l has radius R,-1.5mm and segment 2 radius R,-2.5mm. The current in segment is 1.2A a) Calculate the current density in segment 2. Answer in J/m b) Draw the electric field into each segment (with direction) c) Can the strength of the electric field in segment 2 be calculated? If so, calculate them in V/m. If not, what other info would you need? d) Can the electron drift speed be calculated in segment 2? If so, calculate it in m/s. If not, what other info would you need?

Explanation / Answer

Current density, J = I / A

Due to conservation of current, I1 = I2

J = I2 / A2

J = 1.2 / 1.9635e-5

J = 6.11e4 A/m2

Electric field = J / SIGMA

E = 6.11E4 / 3E7

E = 2.037E-3 V/m (remember we had units A/m2 and 1/ohm*m ....one m will cancel, we are left with A*ohm / m ....Note that A*ohm is unit of V.)

Electron drift speed, v = J / ne

we need charge density