What is the magnitude of the magnetic field of the wire

  • Thread starter oddiseas
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  • #1
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Homework Statement



a long straight 6mm diameter conducting wire is carrying a current of 4A.

1)What is the magnitude of the magnetic field at a point 1mm inside the surface of the wire.

2)what is the magnitude of the magnetic field at a point 2cm from the centre of the wire


Homework Equations



using amperes law:
for part 1 i got 44*10^-9

and for part 2: 50*10^-9

I wnt to make sure i have done it right though, becuase it is a past exam question that i dont have solutions for. So if anyone is good at these questions, it would be helpful to check my answers in case i have stuffed up.


The Attempt at a Solution

 

Answers and Replies

  • #2
kuruman
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The answers to both parts are incorrect.
 
  • #3
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how do you calculate current inside the wire? And do you notice units of all parameters when you calculate?
 
  • #4
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what i tried was:

diameter =6mm. At a point 1mm inside the conducting wire, diameter is 4mm, therefore r=2mm

using amperes law:

∫B⋅ds=μ₀I{Through}

ds=2πr
I{Through}=I∗((πr²)/(πR²)) where R=6mm and r =2mm
B*2πr=I∗((πr²)/(πR²))

B=μ₀Ir/2πR²
B=μ₀(4)(0.002)/2π(0.006)²
 
  • #5
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You wrote diameter = 6mm but then when you put it into eq, you wrote R=6mm.
 
Last edited:

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