Brief question about induced electric fields

In summary, the conversation discusses finding B and H for a solenoid with current I and n turns per unit length, and how a changing current leads to an induced electric field in the opposite direction to H. The conversation also considers the direction of the electric field inside the solenoid and confirms that it goes in a circular direction opposite to the current.
  • #1
bayners123
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Homework Statement



We have a solenoid with current I and n turns per unit length and (neglecting hysteresis) a ferromagnetic core. Find B and H.
Show that when I is varied an electric field is induced and draw it on a diagram.

Homework Equations



[tex]\nabla \times E = - \frac{\partial \bar{B}}{\partial{t}}[/tex]

The Attempt at a Solution



Finding B and H is fine: they come to [tex]\bar{B} = \mu_r \mu_0 n I \hat{\underline{z}}[/tex]
so [tex]\frac{\partial \bar{B}}{\partial t} = \mu_r \mu_0 n \frac{\partial I}{\partial t} \hat{\underline{z}}[/tex].
This implies that when I changes positively an electric field is induced such that the curl of it is in the opposite direction to H.

What I wanted to ask was does this mean that you get an electric field inside the solenoid that sort of goes around in a circle but in the opposite direction to I? I couldn't find it on the internet anywhere so I thought I'd ask to be sure. I've done a (rubbish) diagram of what I mean at http://users.ox.ac.uk/~quee2327/photo.JPG . The magnetic field is meant to be coming out of the page.
 
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  • #2
This implies that when I changes positively an electric field is induced such that the curl of it is in the opposite direction to H. What I wanted to ask was does this mean that you get an electric field inside the solenoid that sort of goes around in a circle but in the opposite direction to I?

Yes, it does.
 
  • #3
Great, thanks! I just wasn't sure of my maths.
 

What is an induced electric field?

An induced electric field is a type of electric field that is created by changing magnetic fields. When a magnetic field is changing, it can create an electric field that is perpendicular to both the changing magnetic field and the direction of motion. This type of electric field is also known as an electromotive force (EMF).

How is an induced electric field created?

An induced electric field is created when there is a change in the magnetic flux through a surface. This can be caused by a changing magnetic field, a moving conductor, or a change in the orientation of a conductor relative to the magnetic field. The induced electric field is always perpendicular to the changing magnetic field.

What is the difference between an induced electric field and a static electric field?

The main difference between an induced electric field and a static electric field is that an induced electric field is created by a changing magnetic field, while a static electric field is created by stationary charges. Additionally, the direction of an induced electric field depends on the direction of the changing magnetic field, while the direction of a static electric field is determined by the sign of the charges creating it.

What are some applications of induced electric fields?

Induced electric fields have many practical applications, such as in generators, transformers, and electric motors. They are also used in technologies such as wireless charging and electromagnetic induction cooktops. Induced electric fields are essential in the production and distribution of electricity.

How can induced electric fields be controlled or manipulated?

Induced electric fields can be controlled and manipulated in various ways, such as by changing the strength or direction of the magnetic field, altering the conductivity or geometry of the conductor, or using shielding materials to redirect or block the field. These techniques are important in various technologies that rely on induced electric fields.

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