# Tagged Questions

The classical theory of electric and magnetic fields, both in the static and dynamic case. Also covers general questions about magnets, electric attraction/repulsion etc. Distinct from electrical-engineering.

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### How strong is Earth's magnetic field in space?

I've been searching around Google and Youtube about the strength of Earth's magnetic field. By the help of wikipedia, I have found out that it's magnitude is 25 to 65 microtesla or 0.25 to 0.65 Gauss ...
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### Relationship Between Conductivity and Lossiness of a material

I read that a material is loss-less if the conductivity is zero. I have always learned that conductivity is a measure of how easily the material can conduct a current. Does this then mean that the ...
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### How to prevent magnetic field from generating in current carrying conductor?

Is there anyway to prevent generating magnet field or nullify it.
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### Hamiltonian formulation of the semiclassical Model of electrons

I'm currently reading the book Solid State Physics by Neil W. Ashcroft and N. David Mermin. In Chapter 12 they introduce the "Semiclassical Model of Electron Dynamics". In short: After having solved ...
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### How to calculate flux density in a toroidal CT that has an electrical line pass through the center?

I have seen the Biot–Savart equation, but I don't know how to apply it. Does the conductor length need to be considered finite and equal to the core length, or will the calculation be for a conductor ...
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### Find magnetic field in a solenoid for different regions?

A steady current I flows along an infinitely long hollow cylindrical conductor of radius R. This cylinder is placed coaxially inside an infinite solenoid of radius 2R. The solenoid has n turns per ...
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### How would I construct an EMI shield for low frequency EMI?

By low frequency, I mean 30-100 Hz. Would a Faraday cage or something like it be feasible? I am trying to shield two separate locations on a high voltage cable.
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### How do you derive Fleming's left hand rule?

How do you derive Fleming's left hand rule? What is the theoretical explanation for the directions of the magnetic field, current and the force on the current for being oriented in that way relative ...
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### why the electromagnetic wave transmits momentum in the direction of the movement?

Ordinarily a transverse wave does not transmit momentum, as it is the case of the well-known sea wave phenomenon. But the electromagnetic radiation has both fields transversal to the movement of the ...
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### Explanation of force amplification inside a solenoid

For a system being actuated by a motor, the force can be amplified by gearing. The energy is being used for force instead of distance, so it produces more torque but moves slower. For a system being ...
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### EMF Induced in a solenoid

When is the emf induced in a solenoid higher,when making or breaking the circuit? Isn't it the same magnitude since change in flux is same in both rhe cases?
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### Clarify example of Faraday's law

Im wondering if it is possible to induce a high voltage current (above 1k Volts), simply using a falling magnet and a copper wire - it probably is, but then what does it take to do so. I've done ...
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### Can antennas work with high frequency EM waves?

Antennas usually work with FM waves, and AM waves, which mostly used in telecommunications. Information is transferred on FM, and AM waves by a transmitter transmitting information on these EM waves. ...
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### Hearing background noise from earphone while there isn't any connection

Once my friend told me that he was listening some background noise while his earphones were not plugged in any device. I didn't believe him but 10 minutes ago I experimented the same. I can certainly ...
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### Repelling a weak permanent magnet with an electromagnet

I have a question about magnetic repulsion. Suppose I have a permanent magnet (axially magnetized) placed on top of the iron core of an electromagnet. I want to switch on the elctromagnet to repel the ...
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### Could a man float in a large enough magnetic field to simulate zero gravity?

I know the magnetic field would need to be very large, but if an organisation like NASA with huge funding and resources could build a large enough device, could a man float in that magnetic field to ...