When a point-shaped electrical charge, with a certain velocity, is launched in a region where there is a magnetic field, depending on from the orientation of the magnetic induction vector, we will see that the charge is subjected to a magnetic force also called the force of Lorentz. Thus, when this charge is launched in a magnetic field, it can assume different types of movement within the field, depending on the direction of its velocity in relation to the magnetic field.
If by chance we place a straight conductor wire immersed in a magnetic field, we will see that this wire is also subject to a magnetic force. What we can see from this interaction is that the magnetic force that acts on a conductor covered by an electric current, when placed in a magnetic field, it is used in a wide variety of devices such as motors, ammeters, voltmeters and galvanometers.
Most of the electric motors that we come across in our daily lives have as their working principle the effect of rotation of the forces that act on the coils placed in a magnetic field. Basically, the principle of electric motors consists of a rectangular-shaped conductor that can rotate around a fixed axis.
Many electrical devices that make use of this operating principle actually work as electromagnetic meters, such as the galvanometer. An electromagnetic meter, a galvanometer, works based on the rotation effect that the magnetic fields cause in the coils, conducting an electric current.
When an electric current flows through an electromagnet, a magnetic field appears around it, which interacts with the magnetic field created by the magnet in the region. The magnetic force that arises from this interaction, between the magnetic field of the magnet and the magnetic field of the electromagnet, moves the electromagnet, which is fixed to a movable shaft, which ultimately displaces the pointer with it.
As we know that the magnetic force is proportional to the electric current, we can say that the greater the electric current, the more the pointer will rotate. When the electromagnet rotates, it compresses a spiral-shaped spring, so the pointer stabilizes when the magnetic and elastic forces balance. The galvanometer is a very sensitive electromagnetic measuring device that can be used to measure electrical currents of low intensity.
O galvanometer, when used to measure electrical current in an electrical circuit, it must have the wire to the electromagnet connected in series. In order to measure electrical voltage in a circuit, the galvanometer must be connected in parallel.
By Domitiano Marques
Graduated in Physics
