Introduction to Electromagnetic Physics
Electromagnetism is a branch of physics that studies the interaction between electricity and magnetism, and its laws and applications. According to the view of modern physics, the phenomenon of magnetism is generated by the motion charge, and thus the content of magnetism must be contained to varying degrees within the electrical range. Therefore, the contents of electromagnetism and electricity are difficult to be completely divided, and "electricity" is sometimes referred to as "electromagnetism". Electromagnetism has evolved from two separate sciences (electricity, magnetism) into one in physics. The complete branch discipline is based on two important experimental findings, namely the magnetic effect of the current and the electrical effects of the changing magnetic field. These two experimental phenomena, together with Maxwell's assumptions about the magnetic field generated by the changing electric field, laid the entire theoretical system of electromagnetism and developed electrical and electronic technologies that have a major impact on modern civilization.
The current carried by the wire creates a magnetic field around it, and the magnetic field lines surround the wire in a concentric pattern.
The current can be measured directly using an ammeter. The disadvantage of this method is that the circuit must be cut off and the ammeter placed in the middle of the circuit. Intermittent measurement of the magnetic field around the current can also measure the current intensity. The advantage is that there is no need to cut the circuit. Instruments that use this method to measure current include Hall effect sensors, current clamps, current transformers, Rogowski coils, and the like.
The discovery of electrons combines the theory of electromagnetism and atomic structure with matter. Lorentz's theory of electrons attributes the macroscopic electromagnetic properties of matter to the effects of electrons in atoms, and uniformly explains the phenomena of electricity, magnetism, and light.
Electromagnetism is a branch of physics. There is a close relationship between electricity and magnetism. Generalized electromagnetics can be said to include electricity and magnetism, but in a narrow sense it is a discipline that explores the interaction between electricity and magnetism. It mainly studies electromagnetic waves, electromagnetic fields and related electric charges, dynamics of charged objects, and so on.