- #1
tiagobt
- 31
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How do I calculate the magnetic field genereated by a very long metal plate with width w and current i flowing along the direction of the largest dimension? If I calculate the intesity of the magnetic field in a point with distance b from the border of the metal plate, I get:
[tex]B = \frac {\mu_0 i} {2 \pi w} \ln \left(1 + \frac w b \right)[/tex]
(using Biot Savart Law to a long wire integrated over the area)
But I saw another solution for this problem with a different answer. This time, Ampere's Law was used along a square path where current flows, getting the following answer:
[tex]B = \frac {\mu_0 i} {2w}[/tex]
My questions are:
1. Why are the answers different?
2. What does the second answer mean, i.e., in which point of space is that field intensity valid? I don't understand how he could not have used a point to calculate the field.
Thanks for the help
[tex]B = \frac {\mu_0 i} {2 \pi w} \ln \left(1 + \frac w b \right)[/tex]
(using Biot Savart Law to a long wire integrated over the area)
But I saw another solution for this problem with a different answer. This time, Ampere's Law was used along a square path where current flows, getting the following answer:
[tex]B = \frac {\mu_0 i} {2w}[/tex]
My questions are:
1. Why are the answers different?
2. What does the second answer mean, i.e., in which point of space is that field intensity valid? I don't understand how he could not have used a point to calculate the field.
Thanks for the help