Find the magnitude of the magnetic field 10 cm from the wire

  • Thread starter Covenant32
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  • #1
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Homework Statement



A) Find the magnitude of the magnetic field 10 cm away from the wire at point P as shown in the picture. The current is directed along the x-axis.

B) Find its direction

Info: I = 5 amps. Point P lies on the Y-axis. Current on the X-axis.

Picture (I have drawn): http://twitpic.com/7e0l7e [Broken]

Homework Equations



I THINK: B=u*I/2*pi*r

The Attempt at a Solution



B = (4pi * 10^(-7)) * 5/2 *pi * .1m = 7.85 * 10^(-8) N

***I am not sure if this is correct. I have no means to check my work, so I am hoping someone can simply tell me whether or not I am correct, and if not, perhaps enlightening me as to which direction I should head to find the right answer. Much thanks.
 
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Answers and Replies

  • #2
Doc Al
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I THINK: B=u*I/2*pi*r
Better to write it like this:
[tex]B = \frac{\mu_0 I}{2 \pi r}[/tex]

Redo your calculation.
 
  • #3
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Better to write it like this:
[tex]B = \frac{\mu_0 I}{2 \pi r}[/tex]

Redo your calculation.

Thank you, Doc Al. I redid my calculation in that format and got 7.96E-7. Does that seem correct?

Again, thank you.
 
  • #4
Doc Al
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I redid my calculation in that format and got 7.96E-7. Does that seem correct?
Not exactly. When you plug in the value of μ0 = 4*pi*10^(-7), that pi will cancel with the pi in the denominator. So you should be able to do the entire calculation without touching a calculator.

Try it one more time. :smile:
 
  • #5
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Not exactly. When you plug in the value of μ0 = 4*pi*10^(-7), that pi will cancel with the pi in the denominator. So you should be able to do the entire calculation without touching a calculator.

Try it one more time. :smile:

Aaah, got it. That should've been evident from the beginning. :redface: Thank you, Doc Al. You have alleviated me some frustration. :smile:
 

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