Introduction
A magnetic field is a region in space containing a magnetic force which can attract or repel other materials affected by its force. Each magnetic field is generated by a circulating field of electrons, or the magnetic domain, that creates a series of magnetic poles. Like electrical charges, magnetic fields can repel or attract one another, depending on their direction. In the study of magnetism, various theories have been developed to explain the behavior of magnetic fields.
Definition
A magnetic field is a region around a permanent or changing electric charge or a permanent magnet, in which a magnetic material such as iron, steel, or copper can experience a magnetic force. This force results from a combination of electric and magnetic fields produced by the charges or magnet. A magnetic field is typically characterized by a vector components of strength and direction.
Sources
Magnetic fields are generated by electric currents, more notably amperes, that move through a conductor such as a coil of wire, or a substance. The magnitude and direction of a magnetic field is dependent on the current and how it is directed through the conductor. Static magnetic fields are generated by permanent magnets, while dynamic magnetic fields are generated from changing electric currents.
Permeability
The ability of a material to affect or be affected by a magnetic field is referred to as its permeability. Some materials are more easily affected by a magnetic field than others. Iron and steel, which contain small amounts of the ferromagnetic elements chromium and nickel, are known to be the most permeable materials. Such materials are used in electromagnets, which are able to amplify the strength of the magnetic field generated by the current passing through them.
Magnetic Poles
The two points at which a magnetic field lines is the magnetic poles which, like electric charges, have opposite polarity. Magnetic poles interact with each other, with like poles repulsing and unlike poles attracting. When placed in a magnetic material, one of the poles can be attracted and stick to the material, an effect known as ferromagnetism. This is why iron and steel are often used in electromagnets, as the resulting magnet sticks to the material, creating a stronger magnetic field.
Lines of Force
Magnetic fields can be depicted schematically in what is known as lines of force, which indicate the direction of the field and its strength. Imagine that the lines of force are extended in a closed loop. The strength of the magnetic field at any point is given by the number of lines that pass through the point in unit time (i.e., flux density).
Applications
Magnetic fields are used in a wide variety of applications. In nature, magnetic fields are found in stars and planets, which can be observed by telescope and studied by physicists. In the biomedical field, they are used to image tissues after they’ve been exposed to a magnetic field. Such techniques can detect tiny changes in cells, allowing for early detection of disease and cancer. Magnetic fields are also important in everyday life, as most electronic devices are based on the principles of magnetism.
Conclusion
Magnetic fields are an important and interesting physical phenomenon, used in a wide variety of applications from amateur experiments to medical diagnosis. The direction and strength of the field is determined by the magnetic poles and the lines of force being produced. A material’s permeability determines how easily it is affected by the magnetic field and the extent to which it can be used in applications.
