Calculating Magnetic Field Intensity Between Two Parallel Wires

In summary: If they have equal, anti-parallel currents, and it's a point that's equidistance from the wires, then the answer has to be zero. Unless you decide to ignore the fact that magnetic fields are vectors.true, they do cancel out. However, there is something else I am missing.anti-parallel.
  • #1
Winzer
598
0

Homework Statement


Two long parallel wires are a center-to-center distance of 1.50 cm apart and carry equal anti-parallel currents of 1.80 A. Find the magnetic field intensity at the point P which is equidistant from the wires. (R = 4.00 cm).

Homework Equations


[tex] B= \frac{u_{0}I}{2\pi r} [/tex] infinite wire

The Attempt at a Solution


Ok I have been workin this problem for a while.
In terms of vectors, the y's cancel out.
For the X direction I get:
[tex] B_{totalx}=\frac{u_{0} I R}{\pi \sqrt( (d/2)^2 +R^2)}[/tex]
I don't get why I am wrong, I took the sum of the b-fields in terms of vectors.
And no the answer is not 0 T!
 

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  • #2
Why do you think that the Magnetic field is not zero?
 
  • #3
Thats what I thought originally , but it is incorrect.
 
  • #4
If they have equal, anti-parallel currents, and it's a point that's equidistance from the wires, then the answer has to be zero. Unless you decide to ignore the fact that magnetic fields are vectors.
 
  • #5
Anti-parallel.
 
  • #6
PiratePhysicist said:
If they have equal, anti-parallel currents, and it's a point that's equidistance from the wires, then the answer has to be zero. Unless you decide to ignore the fact that magnetic fields are vectors.
Thats what I used to think too, but when I entered 0 T it is incorrect.
there is something else I am missing.
 
  • #7
TVP45 said:
Anti-parallel.
got an idea?
 
  • #8
Go back and ask your instructor what he means by anti-parallel. It has more than one meaning. It shouldn't but it does.
 
  • #9
I agree, word choice could be better.
However I don't have contact with my prof. right now, this assignment is due in an hour.
 
  • #10
If I was you I would give your best guess (ignore that you know it's "not right") and argue for points later. Chances are others having the same problem.
 
  • #11
perhaps his answer is wrong by mistake? talk to other people in the class
 
  • #12
he is not, there is an answer I people got. There is some trick though, but my math tells me otherwise,
 
  • #13
PiratePhysicist said:
If they have equal, anti-parallel currents, and it's a point that's equidistance from the wires, then the answer has to be zero. Unless you decide to ignore the fact that magnetic fields are vectors.

? The two B fields add up, they don't cancel!
It's when the currents are in the same direction that the total B field is zero at the point midway between them.
 
Last edited:
  • #14
Winzer said:
[tex] B= \frac{u_{0}I}{2\pi r} [/tex] infinite wire
Good.

The Attempt at a Solution


Ok I have been workin this problem for a while.
In terms of vectors, the y's cancel out.
True.
For the X direction I get:
[tex] B_{totalx}=\frac{u_{0} I R}{\pi \sqrt( (d/2)^2 +R^2)}[/tex]
I don't get why I am wrong, I took the sum of the b-fields in terms of vectors.
Show how you got that answer--it's not dimensionally correct, for one.
 
  • #15
OK, now that I can see your diagram, I see the instructor used anti-parallel in the correct sense.
 

1. How do two parallel wires behave in a circuit?

When two parallel wires are connected in a circuit, they create a path for electricity to flow. The current in each wire flows in the opposite direction, but the magnitude of the current is the same. This results in the wires experiencing a repulsive force, causing them to move away from each other.

2. What is the purpose of using two parallel wires in an electrical circuit?

The use of two parallel wires in a circuit allows for the distribution of electricity to multiple devices or components. It also ensures that the flow of current is balanced and prevents overload in a single wire.

3. How does the distance between the two parallel wires affect the circuit?

The distance between the wires affects the strength of the repulsive force between them. As the distance increases, the force decreases, resulting in a weaker effect on the wires. This can also affect the resistance and capacitance of the circuit.

4. What are some factors that can affect the behavior of two parallel wires in a circuit?

The behavior of two parallel wires in a circuit can be affected by factors such as the type of material used for the wires, the current flowing through them, and the presence of other components in the circuit. Temperature and humidity can also have an impact on the wires' behavior.

5. Can two parallel wires ever attract each other?

In certain cases, two parallel wires can attract each other instead of repelling. This can happen when the currents in the wires are flowing in the same direction, creating a magnetic field that causes the wires to attract. This phenomenon is known as the Ampere force and is only observed in specific conditions.

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