The magnetic field is a kind of invisible and imperceptible impact. The magnetic field occurs naturally in nature, eg in the form of the Earth’s magnetic field. The evidence for its existence is a well-known compass, or more precisely the fact of placing a magnetized and longitudinal object in a particular privileged position, mounted in a way that eliminates friction.
Magnetic field – physical view
Magnetic field is generated by:
- electric charges moving in an orderly manner
- moving charged bodies
- displacement currents in the dielectric
It is formed around any conductor with current, regardless of the material and the conductor type.
Magnetic and electromagnetic fields with varying intensity degrees are present over the entire globe.
- The intensity of Earth’s magnetic field is 100 µT
- for therapeutic purposes (1 – 10mT) sometimes up to 15 mT
- magnetic resonance (MR) field – (0,15-1,5 T)
The magnetic field intensity is the ratio of the force with which field acts in vacuum (perpendicular to its course of action) on the conductor with electric current to the conductor length and current intensity
Magnetic field strength is measured in Tesla [T] or alternatively Gauss units (1 Gauss = 0.0001 T = 0.1 mT)
Magnetic properties of the bodies are related to their magnetize abilities, i.e. to gain characteristics of a natural magnet
Diamagnetic material – slightly weaken the magnetic field. These include: certain gases (hydrogen), water and aqueous solutions of electrolytes, glass, some metals, oxyhemoglobin, vitamins.
Paramagnetic material – magnetic field slightly strengthen. (air, many gases and the majority of metals, hematin, myoglobin, cytochromes).
Ferromagnetic material – generate an additional magnetic field. These are: iron, nickel, cobalt and various alloys, hemoglobin
Magnetic field — types
- Static – the source of which is a permanent magnet. At present there are available various types of magnets. Neodymium magnets are the strongest ones and in spite of their small dimensions they are field sources with very high values.Static magnetic field is generated by the solenoid. This type of field is generated by a constant current flowing through the solenoid.
- Dynamic – which is induced by the electric current flowing through a conductor, alternating dynamic field is generated by alternating currents. The magnetic field shape is directly dependent on the shape of current flowing through the solenoid.