Magnetic field pickup coil

[pritihiviraj]

If we use the coil to measure the magnetic flux leakage of any house hold equipments, what will be the relationship between the {induced voltage, current and phase in coil} and {applied voltage, current and phase of that house hold equipment}?? :bang:

 

[FvM]

Induced voltage will be measured open circuit, means no current in the pick up coil. If you load the coil, the relation between voltage and current depends only on the load.

There's no general answer to your second question. Everything depends on the nature of equipment and the involved magnetic component generating the field.

 

[pritihiviraj]

Is there any phase shift between equipments and induced coils voltage and current??

 

[D.A.(Tony)Stewart]

E fields can be measured with open circuit voltage
H fields can be measured with closed loop current.

Similar to the way that a changing magnetic field generates an electric field, a changing electric field generates a magnetic field. This fact is known as Maxwell's correction to Ampère's law. Maxwell's correction to Ampère's Law bootstrap together with Faraday's law of induction to form electromagnetic waves, such as light. Thus, a changing electric field generates a changing magnetic field, which generates a changing electric field again.

Like all vector fields, a magnetic field has two important mathematical properties that relates it to its sources. (For B the sources are currents and changing electric fields.) These two properties, along with the two corresponding properties of the electric field, make up Maxwell's Equations. Maxwell's Equations together with the Lorentz force law form a complete description of classical electrodynamics including both electricity and magnetism.
( ref Wiki)


There are line voltages with opposite phase and currents which shift from reactive loads.

To understand the Physics, it is useful to learn the math.

**broken link removed**

 

[pritihiviraj]

i would like to know the relation between frequency, voltage and current parameters of the equipment that i want to test and frequency, voltage and current parameters of the coil

 

[BradtheRad]

There is (or was) a storebought pickup coil which you can attach to a telephone handset, to record telephone conversations. It is designed to respond to audio frequencies. Normally you plug it into a tape recorder.

The recorder input (IPod, etc.) has a relatively high impedance. It does not load the pickup coil. Therefore voltage is not attenuated. Current flow is tiny.

If you want, you can attach a resistor as a load. This will reduce voltage. Current flow will be higher.

There is a certain ohm value you can attach, which matches the reactive impedance of the coil, at a given frequency. This is the combination which transfers maximum power.

If you are trying to detect small power levels, or if you are measuring from a distance, then you need a coil with larger Henry value.

 

[pritihiviraj]

Then what is the relation between the frequency, Voltage and Phase shift of induced signal of coil and magnetic field in which the coil has been placed?

 

[FvM]

Induced voltage is the derivative of magnetic flux in the coil. https://en.wikipedia.org/wiki/Faraday's_law_of_induction

Respectively it has 90° leading phase and voltage is rising with frequency.

 

[pritihiviraj]

what will be the phase shift between induced signal and magnetic field??

 

[FvM]

As stated in my previous post.