How does an Ammeter Work?
There are multiple types of ammeters, and each one works slightly different. For example, a moving coil ammeter uses magnetic deflection to allow for the movement of the coil in a magnetic field, which allows the user to measure the electric current in a circuit. Instead of using a moving coil, a moving iron ammeter uses a fixed coil which allows the user to measure the electric current.
Hans Christian Orsted was the first person discovering the effects of a magnet on a compass. He found that when an electric current was flowing near the compass, its needle would be deflected from pointing north. This original tool was developed from a multiplier which used to measure currents. However, it worked only when it was aligned with Earth's natural magnetic field. But an ammeter, which relies on an electromagnetic current running perpendicularly through a conductor, is used today to measure electric currents in a circuit. A perfect ammeter has 0 resistance within the structure, but most ammeters have a minimal and usually trivial amount of resistance that can affect the amps data in a current.