# Orientation of Electric Fields in a Bucking Coil Setup

• Narayanan KR
In summary, the OP is asking about the electric fields induced by the supply and the coils in a parallel wire configuration. The fields will cancel in the centre, but will sum away from the axis on the plane of symmetry.
Narayanan KR
TL;DR Summary
Imagine two series coils carrying a Time varying current such that magnetic fields of both coils oppose each other, what will be the orientation and polarization of the Induced Electric Fields due to changing magnetic fields in the Space between the coils (circled by Orange Box in Fig. 1) ?
Will it be circular as shown by green arrows in Fig. 2 or will it be axial as shown by red arrows in fig. 3 ?

Where is this question from ?
Is this homework ?

Baluncore said:
Where is this question from ?
Is this homework ?
we do projects for educational purpose, This particular Problem came while working on differential mode choke to reduce noise input in electronics, it would help me a lot if someone answers it.

Narayanan KR said:
Will it be circular as shown by green arrows in Fig. 2 or will it be axial as shown by red arrows in fig. 3 ?
I think both electric field distributions described by you will appear. The actual overall electric field distribution may be more complicated. You may need to use 3D electromagnetic simulation software to find accurate answers.

Narayanan KR said:
This particular Problem came while working on differential mode choke to reduce noise input in electronics,
For lumped elements like that, the E-field does not enter into the functional analysis. You are only concerned with the currents and the magnetic flux produced by them. You do not need to try to analyze this lumped component like it's an antenna. If you start talking about GHz circuit analysis, that is a different topic, and much more complicated.

We might, perhaps, consider a simple analogy where we have a pair of parallel wires carrying current in the same direction. Then the wires repel each other because the magnetic fields between them are opposing. The electric field of each wire is directed outwards into space like the bristles of a test tube brush, but between the wires the two electric fields are superimposed, and as they act in opposite directions, they cancel to zero.

Narayanan KR
tech99 said:
We might, perhaps, consider a simple analogy where we have a pair of parallel wires carrying current in the same direction. Then the wires repel each other because the magnetic fields between them are opposing. The electric field of each wire is directed outwards into space like the bristles of a test tube brush, but between the wires the two electric fields are superimposed, and as they act in opposite directions, they cancel to zero.
understood

tech99 said:
We might, perhaps, consider a simple analogy where we have a pair of parallel wires carrying current in the same direction. Then the wires repel each other because the magnetic fields between them are opposing.
It is easy to get that parallel wire situation backwards in your mind. When a short circuit occurs at the load end of a transmission line, the currents are high, equal, and in opposite directions, so the wires initially repel. When the short is cleared, overhead transmission lines swing back together, where they may contact and so short circuit.
During normal mode operation, the magnetic field between two wires is almost doubled, while the external fields tend to cancel, which is one reason why parallel transmission lines have low radiation.

The OP question is not well posed and so is more complex. The magnetic fields of the two coils will cancel on axis, but will sum away from the axis on the plane of symmetry.

Narayanan KR
I think he is asking about electric fields, which is complex. Just because they cancel in the centre does not also mean zero coupling.

tech99 said:
I think he is asking about electric fields, which is complex. Just because they cancel in the centre does not also mean zero coupling.
So you will not counter or invert the relative current direction in your parallel wire example?

Yes, the Op wants electric field induced in space? about the wires and coils.
If the frequency and inductance were very high, the current would be low, so the electric field due to the supply alone would be important. The magnetic field is needed to find the energy radiation direction, the Poynting vector, and so from that, the electric field component in the complex near field.

Narayanan KR

## 1. What is a bucking coil setup?

A bucking coil setup is a configuration of two coils that are wired in opposite directions and placed close to each other. This setup is used to cancel out the magnetic field produced by one coil with the magnetic field produced by the other coil.

## 2. Why is the orientation of electric fields important in a bucking coil setup?

The orientation of electric fields is important because it determines the direction and strength of the resulting magnetic field. In a bucking coil setup, the electric fields of the two coils must be oriented in opposite directions in order to cancel out each other's magnetic fields.

## 3. How does the orientation of electric fields affect the cancellation of magnetic fields in a bucking coil setup?

The orientation of electric fields determines the direction and strength of the resulting magnetic field. When the electric fields of the two coils are oriented in opposite directions, they produce magnetic fields that cancel out each other, resulting in a net magnetic field of zero.

## 4. Can the orientation of electric fields be changed in a bucking coil setup?

Yes, the orientation of electric fields can be changed by reversing the direction of current flow in one of the coils. This will cause the electric fields to be oriented in opposite directions, resulting in the cancellation of magnetic fields.

## 5. What are some practical applications of a bucking coil setup?

A bucking coil setup is commonly used in electronic devices to cancel out unwanted magnetic fields that can interfere with the functioning of the device. It is also used in electrical power systems to minimize the effects of stray magnetic fields on sensitive equipment.

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