波恩的一个动态电磁体的公式

A solenoid is a conducting wire coated with an insulating material, wound tightly in the form of a helical coil. The magnetic field due to a solenoid is the vector sum of the magnetic fields due to its individual turns. Therefore, for an ideal solenoid, the magnetic field within the solenoid is directly proportional to the number of turns per unit length and the current. Conversely, the magnetic field outside the solenoid is zero.
Consider a solenoid with 100 turns wrapped around a cylinder of...

The self-inductance of a circuit, often simply called the inductance, is a purely geometric factor that depends only on the circuit component's structure. More specifically, it depends on the shape and size of the component that lets the flux pass through it, thus inducing an electric field that opposes any current passing through it.
Since the effect of the induced electric field and the back EMF generated depends on the rate of change of current and the self-inductance, the inductance...

A solenoid is a conducting wire coated with an insulating material, wound tightly in the form of a helical coil. The magnetic field for a solenoid is the vector sum of the magnetic field due to its individual turns. For an ideal solenoid, the magnetic field inside is almost uniform and parallel to the solenoid axis, while the magnetic field outside the solenoid is nearly zero.
Each turn in a solenoid can be approximated as a circular current carrying coil that generates a dipole moment. The...

A toroid is a closely wound donut-shaped coil constructed using a single  conducting wire. In general, it is assumed that a toriod consists of  multiple circular loops perpendicular to its axis.
When connected to a supply, the magnetic field generated in the toroid has field lines circular and concentric to its axis. Conventionally, the direction of this magnetic field is expressed using the right-hand rule. If the fingers of the right hand curl in the current direction, the thumb...

Consider a circular loop with a radius a, that carries a current I. The magnetic field due to the current at an arbitrary point P along the axis of the loop can be calculated using the Biot-Savart law.

In electrostatics, the electric field can be written as the negative gradient of the potential. In magnetostatics, the zero divergence of the magnetic field ensures that the magnetic field can be expressed as the curl of a vector potential. This potential is known as the magnetic vector potential.
Consider an ideal solenoid with n turns per unit length and radius R. If I is the current through the solenoid, the magnetic field inside the solenoid is expressed as the product of vacuum...