Current

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[edit] Definition

Current is a term widely used in electonics. Quite often we are interested in its value because components are rated for the maximum current that they can take before they fail, it is useful therefore to be able to calculate and measure current to prevent the release of the "magic smoke". Current is also useful to know if we wish to calculate the power that a circuit consumes (wattage=voltage times current).

Current is the flow of electrons around a circuit. A current is created when there is a voltage applied. The negative pole of a battery or power supply drives the electrons away from it around the circuit(see charged particles)

In a series circuit the current remains constant no matter where it is measured in the circuit. In a parallel circuit the current will have different values depending where in the circuit it is measured. This is the opposite to voltage.

[edit] Measuring Current

We the unit of measure for current is an ampere or amp for short. An ampere is the current created by the application of one volt upon a circuit with a resistance of one ohm. Another way that an ampere can be described is the movement of 6,280,000,000,000,000,000 (6.28 * 10 to the power of 18 or more easily expressed as a coulombe) electrons per second at a point in a circuit. Thats a lot of electrons!

We can measure the current in a circuit using an ammeter (a function of our trusted multimeter), typically in values such as milliamperes (1/1,000th of an ampere denoted as mA) or microamperes (1/1,000,000th of an ampere denoted as µA). In order to measure amps we must break in to the circuit with a multimeter i.e. connect the meter in series (remember that the current has a constant value in a series circuit.)

[edit] Calculating Current

Current can be calculated by using ohm's law. It is expressed as I within the formula.