The displacement current is an important concept in electromagnetism that is described by the fourth Maxwell equation. It is a time-varying electric field that arises from the changing electric flux through a surface. It is closely related to the concept of a changing magnetic field, which is described by the third Maxwell equation.
The displacement current and the conduction current are both types of electric currents, but they have different origins. The conduction current is the flow of charged particles, such as electrons, through a conductive material. In contrast, the displacement current is a time-varying electric field that arises from the changing electric flux through a surface.
The displacement current plays a crucial role in the generation and propagation of electromagnetic waves. In fact, it was first introduced by Maxwell to explain the propagation of electromagnetic waves through empty space. Without the displacement current, the fourth Maxwell equation would not be consistent with the other three equations and would not be able to fully describe electromagnetic phenomena.
The displacement current is calculated using the fourth Maxwell equation, which states that the curl of the magnetic field is equal to the sum of the conduction current and the displacement current. In practice, the displacement current is often calculated indirectly by measuring the changing electric flux through a surface and using this to determine the resulting displacement current.
The displacement current has many important applications in modern technology. It is crucial for the functioning of wireless communication systems, such as radio and television broadcasting, as well as cellular phones and Wi-Fi. It is also used in medical imaging techniques, such as MRI, and in particle accelerators. Additionally, the displacement current plays a key role in the design and operation of electrical circuits and devices.