In free space (vacuum) these two vector fields are related by the following equation: They are called B-field (also called magnetic induction) and H-field (also called magnetic field strength). ![]() Definitions and Units of Measurementīefore we start talking about magnetic flux, we have to talk about the two vector fields that describe the magnetic field. Magnetic fields can be further visualized by using iron filings or magnetic field viewing film. The strength of the field is visualized by the spaces between the magnetic flux lines. Magnetic fields are usually visualized by magnetic flux lines. The magnetic field is a vector field because it can be specified by both direction and magnitude. The Earth produces its own geomagnetic field that extends from the Earth’s interior into space and is used for navigation and protects us from the deadly solar wind.īulky horseshoe magnets made from Alnico were used in magnetrons before the development of much less bulky ferrite and rare earth magnetsĪ magnetic field is a region around a permanent magnet or a moving electric charge within which there is a magnetic force acting on moving electric charges and ferromagnetic materials. We are surrounded by magnetic and electromagnetic fields. This includes transformers, electric motors and generators, various drives, electromagnetic clutches and brakes, antennas, and waveguides. Don’t forget about a lot of stuff that works using magnetic and electromagnetic fields. Many smartphone cases use a magnet in their cover to control the smartphone: the phone can sense an open cover and display a lock screen or clock screen. They are on your fridge, in your fridge, in your computers, tablets, and smartphones, in electric motors, in your ears (neodymium magnets in earbuds and magnetic earrings), in various electric motors in cars, trucks, DVD players, and computer hard drives. However, before the middle of the 20th century, there were only a few magnets in our homes - a magnet in a loudspeaker of a radio receiver, telephone, and probably several cabinet magnetic latches. A magnet in a smartphone speaker can be found in the pocket of every person. The apparatus used to measure magnetic flux is called a fluxmeter,it consists of coils and electronics which evaluate the voltage change in the coil to measure the magnetic flux.We are surrounded by magnets in our daily life more than ever. The emf causes the current to flow in the coil hence producing electricity. A changing magnetic flux induces emf in a coil. Most common generators use the principal of magnetic flux to produce electricity. This is the principle on which an electrical generator works. According to Faraday’s law: E=-dφ/dt, where E is the EMF, and the derivative is of Φ, the flux through a surface, with respect to time, T. The electromotive force is produced when a changing magnetic flux is passes through a conductive coil. In electromagnetism a magnetic flux passing through an open surface is of great importance. A closed surface is a surface like a sphere or disk. ![]() Φ=∫∫B.ds where is the magnetic flux B is the magnetic field, S is the surface (area) and '.' denotes the dot product, Magnetic flux through a closed surfaceĪccording to Gauss’s law of magnetism, the total magnetic flux through a closed surface is equal to zero. The integral of the magnetic flux through a surface S is defined as the integral of magnetic field over the area of the surface S. If the surface is placed perpendicular to the field the area vector forms an angle of 0 with the field and hence the magnetic flux would be greatest. Where the surface S is a planar surface with area A, and the magnetic field is constant with magnitude B, a simplified version of the formula can be used: Φ=B.A Cosθ If the surface is placed parallel to the magnetic field the area vector will form an angle of 90 degrees with the field and as a result the magnetic flux would be zero. The magnetic flux is defined by the integral of the magnetic field over the area of the surface. The magnetic flux through a surface is directly proportional to the net density or number of magnetic field lines passing through that surface. More generally it is the scalar product of the magnetic field and the area vector. The product of a magnetic field passing through a surface placed perpendicular to the field is known as magnetic flux.
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