# Tag Info

### What is the meaning of $\vec H$ with respect to the total field?

Here the problem is that you are using too many notations and you are changing them constantly. The master equation in electrostatics : $$\vec{D}= \epsilon_0 \vec{E} + \vec{P}.$$ (i) $\vec{D}$ is ...
1 vote
Accepted

### How does a magnetic field interact?

What is happening in the case of a magnetic field? It's not like the atoms have a brain. Something must be making them interact with the field. For the sake of simplicity, I'll just talk about ...
1 vote

### How does a magnetic field interact?

Gravity at first was explained as an action at a distance. The Newton theory fitted so well that the same idea was used by Coulomb for electrostatic and even by Ampere in its first theory of the force ...

### How does a magnetic field interact?

The key word here is "field": everywhere there is an electric and magnetic field produced by electric and magnetic sources (and actually they are two sides of the same electromagnetic field)....

### When a magnetic ball passes through a copper pipe vertically

In simple terms compare your arrangement to a vertical solenoid with the ends connected together and a magnet dropping through it. An induced current passes through the solenoid which sets up a ...

### Where does the energy for magnetizing a metal come from?

As you said, magnetising a material does require energy. It might seem counterintuitive that a magnetised material can magnetise other ferromagnetic materials (objects) without losing its own magnetic ...

### Magnetic Scalar Potential of Infinite Wire

It depends on the physical interpretation of the quantities. In other contexts, $\phi$ would need to be single valued like if it represented temperature for example. In the context of magnetostatics, ...

### How current is induced when there is a change in external magnetic field?

I'm not sure how to explain 'how', because Faraday's law of induction is a fundamental law of Physics, and asking 'how' is asking why there is such a law. There just is. It's not actually current ...
Accepted

### Explaining Faraday's Law With Lorentz Transformations of $E$ and $B$ Fields

Just a small detail, Faraday's law is about inducing electromotive forces (emf's), not currents. To make the link between current and emf, you'll need to go beyond Faraday's law and make some ...
1 vote

### Voltage across rod in time varying magnetic field

If the (time-varying) field surrounds the wire equally to the right and left of the wire, symmetry surely dictates that the voltage is zero: neither end of the rod gains a charge. Try formulating a '...
1 vote
Accepted

### Are the $H$ and $M$ fields parallel?

They are for e.g. diamagnets and paramagnets. However, ferromagnets (and antiferromagnets) maintain their magnetization, even when the magnetic field goes to zero (hysteresis). Therefore, in those ...

### Could a closed looped of wire with current move itself?

There are two fundamental reasons why this doesn't work like that: Lenz's law: the direction of the electric current induced in a conductor by a changing magnetic field is such that the magnetic ...

### Measuring the magnetic field strength on the surface of a neodymium magnet (without a gaussmeter)?

The Earth is not just like a bar magnet, not really, right? Aren't there 4 types of magnetism: permanent, electro, static and geo? It seems basic, but it's not accurate at all. Like the statement ...
1 vote

### Electron Orbit at the Null Point (DC sputter coating)

In general you would use magnetic fields to steer an electron beam, not to accelerate it. Typically, sputtering does not need magnets. It uses heat to boil atoms off a source. The atoms fly everywhere ...
1 vote

### Can the magnetic field do work?

A simple case... Parallel wires carrying currents in the same direction will attract each other and do work on each other if they are allowed to come together against restraining forces. Wire X sits ...

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