How a diode works
A diode is what is known as a two-terminal device. This means that it has two electrodes through which current can flow. The primary use of a diode is to keep a current only flowing in one direction. This is what is commonly known as the rectifying function of a diode. A diode, when functioning properly, will allow current to only flow in one direction (known as the forward direction) and halt and current in the other direction (reverse direction). Diodes, in addition to their rectifier function, can be used to turn alternating currents (AC) into direct durrents (DC).
How an ammeter works
Ammeters are used to measure electric current within a circuit. Currents are measured in the unit of the ampere, which gives the ammeter its name. Ammeters generally use magnetic deflection to measure electrical current. The electric current passes through a coil, which causes a magnetic field to be generated. This magnetic field causes the coil to move or "deflect." The movement of the coil is measured and from this the strength of the electric current can be calculated.
How diodes work within an ammeter
One of the most important issues for an ammeter is that current is not allowed to flow back in the opposite direction through the coil. Even a partial reversal of the electric current will cause an interfering magnetic field. This will counteract the first magnetic field, causing an alteration of the coil's deflection which will, in turn, cause the measurement of the current to be lower than it actually is. Diodes can also be used to help measure the electric current from an AC power source by converting it into DC.
Tags: electric current, magnetic field, current only, measure electric, measure electric current, through coil
