What is Lenz's Law?

Induced electromotive force tends to generate current, and the direction of current tends to prevent the change of magnetic flux that generates induced electromotive force. Lenz's law formula Lenz's law is an electromagnetic law, and the direction of induced electromotive force is obtained by electromagnetic induction. Which can determine the direction of electromotive force generated by electromagnetic induction. It was discovered by Russian physicist Heinrich Friedrich Leng Ci 1834. Lenz's law is the concrete embodiment of the law of conservation of energy in electromagnetic induction. Lenz's law can also be expressed as: the role of induced current is always the reason to resist induced current.

The key point is that the flux resistance of the induced current causes the change of the original flux of the induced current, rather than resisting the original flux. If the primary magnetic flux increases, the magnetic flux of the induced current must be opposite to the primary magnetic flux in order to resist the increase of the primary magnetic flux; If the primary flux decreases, the flux of the induced current must be in the same direction as the primary flux if it wants to resist the decrease of the primary flux. After correctly understanding the meaning of the above law, we can use Lenz's law to judge the direction of induced current according to the following procedures: a. The direction of primary magnetic flux passing through the circuit and whether it increases or decreases; B, according to the above meaning expressed by Lenz's law, determining the direction of the magnetic flux generated by the induced current in the loop; C according to the direction law of magnetic field generated by loop current in the loop (right-handed spiral law), the direction of induced current is determined by the direction of magnetic flux of induced current. In addition, "blocking" cannot be understood as "blocking". It should be recognized that the primary magnetic field is active and the magnetic field that induces current is passive. The primary magnetic flux will still change and cannot be stopped, but the magnetic field of induced current only plays a blocking role. The existence of induced current magnetic field only weakens the change speed of the total magnetic flux passing through the circuit, without changing the change characteristics and direction.