Publish Time: 2023-09-20 Origin: Site
We learned about induced electromotive force, Electromotive Force=EMF. So, if the induced voltage is connected in a closed circuit, does current flow?
Here is the list
The direction of the force on the wire
Principle of induction electric motor
What is the current of electric motor
We already know that when the guide rod moves to the right, an electromotive force is generated at its two ends. Using the right-hand rule, it's easy to judge whether the upper is positive or the lower is negative: let the magnetic field pass through the palm of the right hand, and the thumb points to the movement of the guide rod. The direction of the four fingers is the direction of the induced current. Bind/Bin represents the magnetic field generated by the induced current, which is opposite to the original magnetic field. We can combine the Lorentz force principle on the conducting wire in the magnetic field to draw the conclusion that the wire is forced to the left: let the magnetic field pass through the palm of the left hand, the four fingers point in the direction of the current, and the thumb indicates the direction of the current. The direction is the direction in which the wire is stressed.
In fact, induction electric motor combine these two fundamental principles: Lafayette's principle of electromagnetic induction and the principle of the Lorentz force of a current-carrying wire in a magnetic field. The principle of induction causes an electric current in a closed conductor of a rotor (rotating induction electric motor) or moving parts (linear induction electric motor), while the Lorentz principle causes a force to be applied to a live conductor. A force or torque moves a moving part or rotor. Small induction electric motor actually use several fundamental laws of physics that I hadn't noticed before.
A closed conductor induces a current in a rotating magnetic field. Recall the right-hand rule: let the magnetic field pass through the palm of the right hand, with the thumb pointing in the direction of the rod movement, and the four fingers pointing in the direction of the induced current. The closed conductor in the figure is exactly horizontal. For the outer side of the closed conductor, the magnetic field is perpendicular to the screen outward, and the magnetic field rotates clockwise, which is equivalent to the conductor moving downward. Using the right-hand rule, let the magnetic field pass through the palm, i.e. the palm is aligned with the screen. The thumb points in the direction of the conductor's movement, that is, down, and then the four fingers point to the left, indicating that the current flows to the left. In the same way, it can be judged that the current direction of the inner conductor is to the right, which just constitutes a loop.
There is an induced current, and the current is in a magnetic field, then the conductor will be stressed. Using the Lorentz force law, let the magnetic field pass through the palm of the left hand, with the four fingers pointing in the direction of the conductor's current, and the thumb in the direction of the conductor's force. It is easy to judge that the outer conductor of the closed loop is forced upward, and the inner conductor is forced downward, and a pair of forces just form a moment, which makes the closed conductor rotate. Of course, the actual electric motor winding has many wires, and the closed loop is formed by the conductor and the structure at both ends (squirrel cage induction electric motor).
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