About induced electromotive force. What is the induced EMF formula?

The induced electromotive force generated by the change in the magnetic field due to the immobility of the circuit is called induced electromotive force.

Induced causes of electromotive force.

Maxwell proposed that a changing magnetic field excites a new electric field in the space around it, called an induced electric field or vortex electric field. The charge in the electric field is subjected to the induced electric field force, which is a non-electrostatic force that produces an electromotive force.

Characteristics of induced electric fields.

1. The induced electric field is excited by a changing magnetic field.

2. The induced power line is closed.

3. The vortex electric field is not a conservative force field, and the concept of potential energy cannot be introduced.

4. Maxwell, who has an electric field force for the charge in it, further believed that the vortex electric field excited by the changing magnetic field always exists objectively, regardless of the existence of a conductor loop. That is, there are two forms of electric fields in space: electrostatic fields excited by electric charges and vortex electric fields excited by varying magnetic fields. Use.

w=fscosa, which is related to the angle between the force and the direction of motion. Looking at Figure 4-5-1, the electric field lines are circular, and the direction of the force is also circular, so the positive charge travels along it, and the cosa is always positive or negative, so the work done must not be zero. And the electric field lines of the electrostatic field are always in one direction, you assume that they are parallel, draw a circle in the parallel lines with directions, and the cosine value of the angle between the direction of motion and the direction of the parallel line is positive for a while and negative for a while, so the work done when you finally return to the origin is zero.

The Lorentz force doesn't do work in the first place, because the Lorentz force is always perpendicular to the trajectory of the electron.

It's like circular motion that doesn't do work.

The one that can move electrons is called non-electrostatic force and can be chemical energy, mechanical energy, and light energy.

In short, energy can move electrons.

But Lorentz doesn't work, it doesn't work.

e nδ t (universal formula). e: Induced electromotive force.

v), n: number of turns of the induction coil, Wu Liang δ t: magnetic flux.

Rate of change. According to Faraday's law of electromagnetic induction.

The magnitude of the induced electromotive force is e=n t, when the magnetic induction intensity.

When the circuit area is unchanged and the area of the circuit is changing, the electromotive force in the circuit is the dynamic electromotive force.

Therefore, such an experiment can be designed, and the magnetic flux through the loop changes when the magnetic flux of the gold cavity circular transport rod AB moves to the right at a uniform speed, indicating that there is an induced electromotive force in the loop.

According to Faraday's law of electromagnetic induction, the average electromotive force in this process can be calculated e=b s t=blvt t=blv, and because only the metal rod ab is moving in the whole circuit, that is, the electromotive force of the loop is only contributed by ab, which means that the dynamic electromotive force generated by the metal rod ab due to translation is e=blv.

Mechanism of induced electromotive force generation:

1. The changing magnetic field produces a vortex electric field, which produces a force on the free charge in the closed circuit placed in it, so that it moves in a directional cavity to form a current, and the magnitude of the electromotive force is equal to the field strength of the vortex electric field.

Credits for one week along this closed loop.

2. The essence of induced electromotive force is induced by the electric field.

The force transport charge is formed by free charge and is generated by changes in the magnetic field.

The formula is as follows:

1. E nδ t (universal formula) {Faraday's law of electromagnetic induction, E: induced electromotive force (V), N: number of turns of the induced coil, δ t: rate of change of magnetic flux};

2. E BLV vertical (cutting magnetic inductance line movement) {L: effective length (m)} When the magnetic field changes or, the induced electric field is generated, and the electric field line of the induced electric field is a curve perpendicular to the magnetic field. If there is a closed conductor in space, the free charge in the conductor will move directionally under the action of the electric field force and produce an induced current, or an induced electric force will be generated in the conductor. Suspicion of group cheating.

1. The induced electromotive force is caused by the change of magnetic flux, which is caused by the change of magnetic induction intensity, and the dynamic electromotive force is caused by the change of magnetic flux due to the movement of the coil.

2. Induced electromotive force properties: when the coil (conductor circuit) does not move and the magnetic field changes, the induced electromotive force excited in the road when the magnetic field changes.

3. Dynamic electromotive force properties: the electromotive force generated by the conductor at both ends perpendicular to the magnetic field and the direction of motion in the magnetic field perpendicular to the direction of the magnetic induction line.

First, the meaning is different:

Induced electromotive force: When the conductor does not move, the magnetic field changes, resulting in a change in magnetic flux, causing a change in electromotive force.

Kinetic electromotive force: The magnetic field strength does not change, and the movement of the coil causes the magnetic field around him to change how much the magnetic flux changes, causing the electromotive force to change.

Second, the role is different;

The essence of the kinetic electromotive force is the effect of ampere force, and the essence of the induced electromotive force is the effect of the electric field. At the high school level, it can be understood that the kinetic electromotive force is the electromotive force generated by the movement of the conductor, and the induced electromotive force is the electromotive force generated by the change of magnetic flux.

The calculation method of the kinetic electromotive forceis the angle between v and b, is the angle between dl and v b.

Determination of the direction of the kinetic electromotive force:

Direction of Kinetic EMF: Towards the direction of the non-electrostatic field, determined by the right-hand rule.

determine the magnitude and direction of the magnetic field of the current-carrying wire;

The above content reference: Encyclopedia - Kinetic electromotive force.

The formula is as follows:

1. E nδ t (universal formula) {Faraday's law of electromagnetic induction, E: induced electromotive force (V), N: number of turns of the induced coil, δ t: rate of change of magnetic flux};

2. E BLV vertical (cutting magnetic inductance line movement) {L: effective length (m)}

3. EM NBS (maximum induced electromotive force of alternator) {em: induced electromotive force peak};

4. E bl2 2 (one end of the conductor is fixed to rotary cutting) {angular velocity (rad s), v: velocity (m s)}.

The magnetic field excites an induced electric field in the space around it, which forces the charges in the conductor to move directionally to form an induced electromotive force.

1. Induced electromotive force: the electromotive force generated in the wire when the wire is weak and the magnetic field changes with time.

Cause: Generated by an induced electric field.

Causes of the change in magnetic flux: The change in magnetic flux caused by the change in b, where the non-electrostatic force is the electric field force of the induced electric field on the free charge.

2. Kinetic electromotive force: the electromotive force generated by the change of magnetic flux caused by the movement of the conductor does not change the magnetic field.

Cause: Produced by the Lorentz force experienced by the charge as it moves in a magnetic field.

The reason for the change in magnetic flux: the part of the conductor that cuts the magnetic inductance line during the motion of the cavity, in which the non-electrostatic force is the component of the Lorentz force by the free charge in the conductor along the direction of the conductor.

Answer]: According to Maxwell's induced electric field hypothesis: a changing magnetic field excites an induced electric field around it.

This electric field force has the ability to push the charge in the conductor to do work, which is the induced electromotive force. It must be made clear here that according to Faraday's law of electromagnetic induction, as long as there is a change in the magnetic flux in the loop, there is an induced electromotive force in the loop, that is, as long as there is a change in the magnetic field in space, then there is an induced slow-cracking electric field in the space, and the electric field has the ability to push the charge to do work, so once the path between any two points in the changing magnetic field space is determined, then the ability of the induced electric field force (non-electrostatic mode field force) to do work on the charge on this path is determined, Therefore, the electromotive force along this path between these two points is uniquely determined, regardless of whether a conductor or insulator is placed along this path.

It represents only the ability of the non-electrostatic force to do work between two points along this path.