Magnetic field of a straight current-carrying conductor

In summary: In that case, the current would vary with frequency, and the phase shift would be due to the changing electric field at the antenna.
  • #1
PhysicsTest
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Homework Statement
To find the magnetic field in a straight current carrying conductor due to sine wave at a distance x on its perpendicular bisector.
Relevant Equations
##B = \frac {\mu_0 I 2a} {4\pi x\sqrt{x^2 + a^2}}##
It is not a direct home work problem, i was thinking if a sine wave current passes through the straight current carrying conductor, what will be the magnetic field. For the DC current I know the formula as below.
##B = \frac {\mu_0 I 2a} {4\pi x\sqrt{x^2 + a^2}}##
Let the current be ##I = I_0\sin(\omega t)## then will the magnetic field be
##B = \frac {\mu_0 I_0\sin(\omega t) 2a} {4\pi x\sqrt{x^2 + a^2}}##
 
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  • #2
PhysicsTest said:
Homework Statement:: To find the magnetic field in a straight current carrying conductor due to sine wave at a distance x on its perpendicular bisector.
Relevant Equations:: ##B = \frac {\mu_0 I 2a} {4\pi x\sqrt{x^2 + a^2}}##

It is not a direct home work problem, i was thinking if a sine wave current passes through the straight current carrying conductor, what will be the magnetic field. For the DC current I know the formula as below.
##B = \frac {\mu_0 I 2a} {4\pi x\sqrt{x^2 + a^2}}##
Let the current be ##I = I_0\sin(\omega t)## then will the magnetic field be
##B = \frac {\mu_0 I_0\sin(\omega t) 2a} {4\pi x\sqrt{x^2 + a^2}}##
Could you attach a diagram showing what ##x## and ##a## are in your question?

And yes, if the wavelength of the B-field sinusoid (propagating at c) is long compared to how close to the wire you want your solution to work, then you just multiply by the sinusoid function itself. If that condition does not hold, then there will be a phase shift between the driven current in the wire and the B-field sensed away from the wire. Does that make sense?

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magcur.html

1601159562993.png
 
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  • #3
The diagram is
1601186189605.png

berkeman said:
If that condition does not hold, then there will be a phase shift between the driven current in the wire and the B-field sensed away from the wire.
How do I calculate the phase shift? Can you provide a hint, I will attempt.
 
  • #4
It is not very realistic to let the current vary with such a high frequency that the propagation to point P is influenced, without considering what happens to the charge in the conductor.

Perhaps you want to look at the phenomena associated with a radiating dipole ?
 
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1. What is a magnetic field?

A magnetic field is a region in space where a magnetic force can be detected. It is created by moving electric charges, such as those found in a current-carrying conductor.

2. How is a magnetic field created by a straight current-carrying conductor?

When an electric current flows through a straight conductor, it creates a circular magnetic field around the conductor. The direction of the magnetic field is determined by the direction of the current, following the right-hand rule.

3. What factors affect the strength of the magnetic field?

The strength of the magnetic field created by a straight current-carrying conductor is affected by the magnitude of the current, the distance from the conductor, and the permeability of the surrounding medium. The strength of the magnetic field decreases as the distance from the conductor increases.

4. How is the direction of the magnetic field determined?

The direction of the magnetic field is determined by the direction of the current. Using the right-hand rule, if the thumb of the right hand points in the direction of the current, the fingers will curl in the direction of the magnetic field.

5. What are some real-world applications of the magnetic field of a straight current-carrying conductor?

The magnetic field created by a straight current-carrying conductor has many practical applications, such as in electric motors, generators, and transformers. It is also used in magnetic resonance imaging (MRI) machines and particle accelerators.

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