Magnetic Fields & Metal: Exploring Currents & Brakes

[brainyman89]

let's say we have a square piece of metal and we put this piece in a variable magnetic field, would it get heated? is this the idea of a current?

If we have a rotating metal disk (as the case of a saw for instance), and then we put this rotating disk in a constant uniform magnetic field such that angle between normal vector and B vector is 0 and is not changing since the disk is rotating along the normal axis, would this disk stop rotating? if yes how comes eddy currents are induced though we are not changing any of these area, B nor the angle? if no then what is the idea of creating brakes by eddy currents?

if we have a short piece of straight rectilinear wire in motion with velocity V in a uniform constant magnetic field, would we have a potential difference(voltage) on the edges of this wire? if yes how comes we got induced emf without changing any of these area, B nor the angle?

thanks in advance

 

[brainyman89]

anybody?

 

[brainyman89]

then what is the idea of eddy current

 

[willum97]

if we have a short piece of straight rectilinear wire in motion with velocity V in a uniform constant magnetic field, would we have a potential difference(voltage) on the edges of this wire? if yes how comes we got induced emf without changing any of these area, B nor the angle?

thanks in advance

If you place 2 sliders in touch with the opposite edges of the wire, and say the sliders are stationary relative to the magnetic field, then a voltage is generated between the sliders. If there are no sliders and the B field is not uniform over the length of this wire, then there will be Eddy currents.

Your question is similar to the Hall effect, although in that case only the electrons are moving in a stationary magnetic field and there are no sliders but electrodes stationary with a wire and B field.

 

[sardar]

I would like to address the question about magnetic fields and metal in the context of electromagnetic induction and the principles of electromagnetism. When a piece of metal is placed in a variable magnetic field, it can indeed get heated due to the production of eddy currents. These currents are induced in the metal as a result of the changing magnetic field, creating a closed loop of current within the metal. This flow of current produces heat due to the resistance of the metal, similar to how a heating element works in an electric stove.

In the case of a rotating metal disk in a constant magnetic field, the disk will indeed experience a braking force due to the production of eddy currents. This is because the rotating disk is cutting through the magnetic field, inducing currents in the disk. These currents then produce their own magnetic field, which interacts with the original field and creates a force that opposes the rotation of the disk. This is the principle behind electromagnetic brakes, where the strength of the braking force can be controlled by varying the strength of the magnetic field.

In the case of a straight rectilinear wire in motion in a uniform magnetic field, there will indeed be a potential difference (voltage) induced along the edges of the wire. This is due to the same principle of electromagnetic induction, where a changing magnetic field induces a current in a conductor. In this case, the motion of the wire through the magnetic field creates a changing magnetic flux, which induces a current and therefore a potential difference along the wire.

Overall, the key idea behind these phenomena is the relationship between changing magnetic fields and the production of eddy currents, which in turn can produce heat, braking forces, and induced voltage. This is a fundamental principle of electromagnetism and has many practical applications in fields such as engineering and physics. I hope this explanation helps to clarify these concepts.