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The most common description of the electromagnetic field uses two three-dimensional vector fields called the electric field and the magnetic field.These vector fields each have a value defined at every point of space and time and are thus often regarded as functions of the space and time coordinates.
Similarly, if only the magnetic field (B) is non-zero and is constant in time, the field is said to be a magnetostatic field. However, if either the electric or magnetic field has a time-dependence, then both fields must be considered together as a coupled electromagnetic field using Maxwell's equations. [9]
A sample is first placed in a constant magnetic field and if the sample is magnetic it will align its magnetization with the external field. The magnetic dipole moment of the sample creates a magnetic field that changes as a function of time as the sample is moved up and down. This is typically done through the use of a piezoelectric material ...
To concentrate the magnetic field in an electromagnet, the wire is wound into a coil with many turns of wire lying side-by-side. [2] The magnetic field of all the turns of wire passes through the center of the coil, creating a strong magnetic field there. [2] A coil forming the shape of a straight tube (a helix) is called a solenoid. [1] [2]
Magnetic field (green) induced by a current-carrying wire winding (red) in a magnetic circuit consisting of an iron core C forming a closed loop with two air gaps G in it. In an analogy to an electric circuit, the winding acts analogously to an electric battery, providing the magnetizing field , the core pieces act like wires, and the gaps G act like resistors.
The definitions for monopoles are of theoretical interest, although real magnetic dipoles can be described using pole strengths. There are two possible units for monopole strength, Wb (Weber) and A m (Ampere metre). Dimensional analysis shows that magnetic charges relate by q m (Wb) = μ 0 q m (Am).
Electromagnetic testing (ET), as a form of nondestructive testing, is the process of inducing electric currents or magnetic fields or both inside a test object and observing the electromagnetic response. If the test is set up properly, a defect inside the test object creates a measurable response.
Schematic diagram of Gouy balance. The Gouy balance, invented by the French physicist Louis Georges Gouy, is a device for measuring the magnetic susceptibility of a sample. . The Gouy balance operates on magnetic torque, by placing the sample on a horizontal arm or beam suspended by a thin fiber, and placing either a permanent magnet or electromagnet on the other end of the arm, there is a ...