A galvanometer uses movements of a coil within a magnetic field or a magnetic needle to measure or detect a small electric current. The galvanometer was the first instrument that scientists used to pick up and quantify electrical currents, and these devices were the first to locate electrical activity in the brain and heart.
The first scientist to observe that a wire with current could deflect a magnetic compass needle was Hans Oersted, who described the phenomenon in 1820. The most common modern applications for a galvanometer deal with control and positioning systems. Mirror galvanometer systems function as beam steering or beam positioning elements within systems for laser scanning. Closed loop mirror galvanometers have applications in laser engraving, laser sintering, stereolithography and laser bean welding, as well as laser television and displays and retinal scanning.
Open loop mirror galvanometers primarily function within barcode scanners that use lasers, as well as in some printers, space systems, military applications and imaging programs. Uses that require a significant level of vacuum make their non-lubricated bearings quite useful. The positioning servos in hard drives and compact disk players also use a galvanometer mechanism, and all of these use the moving coil type of galvanometer to keep the overall mass of the system low.Learn More
Dynamos produce electric current by rotating a wire within a magnetic field. Another method rotates a permanent magnet around coils of wire. Both processes produce alternating current because the wire passes between two magnetic poles every half turn. A commutator can turn the alternating current into direct current pulses, a common practice in early days before alternating current became the standard.Full Answer >
Windmills produce electricity by electromagnetic induction, the process in which the movement of magnets in a magnetic field generates electricity. In a windmill, when wind moves the blades of the windmill that move the rotor, the rotor rotates a shaft that holds magnets in the magnetic field of the generator, generating alternating current that is sent along power lines.Full Answer >
Florida State University defines Lenz's Law as an induced electromotive force that generates a current that induces a counter magnetic field opposing the magnetic field generating the current. Lenz's Law was first discovered by the Russian physicist Heinrich Lenz in 1834.Full Answer >
In the early 20th century, Tesla coils provided high frequency and high voltage electricity for radio transmission, X-ray machines, electro-therapy and early particle accelerators. Other electrical generation methods have since eclipsed the Tesla coil, so in modern times they have little practical value except for high voltage demonstrations.Full Answer >