Calculating current given the current density and area

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The discussion revolves around a problem calculating the current in a wire given its current density and cross-sectional area. The user initially calculates the current as 9404.7 A but later realizes a unit conversion error, mistaking mm² for m². The correct conversion shows that 1 mm² equals 10^-6 m², which significantly affects the current calculation. Consequently, the user also reevaluates the time required for electrons to pass through the wire, leading to a revised understanding of the problem. The key takeaway is the importance of accurate unit conversions in electrical calculations.
CivilSigma
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Hello, I am having trouble getting the correct solution to the following problem, even though I think my steps all are correct! What did I do wrong?

1. Homework Statement

A wire has a current density of 6.67 × 10^6 A/m^2. If the cross-sectional area of the wire is 1.41 mm^2, what current does the wire carry?

With this current, how much time is required for 4.77 × 1020 electrons to pass any point on the wire?

Homework Equations


Current = current density * area
Current = charge/time So, time = charge / current

The Attempt at a Solution


For the first part I get: Current = 6.67\cdot10^6 A/m^2 * 1.41\cdot10^{-3} =9404.7A
For the second part I get: time=\frac{4.77*10^{20} electrons \cdot 1.602\cdot10^{-19} C/electron}{9404.7A}=0.00813s

And as I stated, I'm not getting the correct answer. As you can see my units all match up. Do you see a math error? Or have I misunderstood a concept.

Thank you,
-Sakon
 
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sakonpure6 said:
Do you see a math error?
Yes. Check your units one more time.
 
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Thank you, know I know 1mm^2=10^-6 m^2
 
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