Electromotive force (emf)] is the electrical energy produced by a non-electrical source. It is created by converting other forms of energy into electrical energy, such as batteries (which convert chemical energy) or generators (which convert mechanical energy). It is more commonly referred to as voltage.

A Volt is the Standard International (SI) unit of measurement for electromotive force and is defined as the electromotive force required to produce 1 Watt of power at a current of 1 Amp

Current is the movement of charged particles (electrons) through a conductor when an emf is applied.

Amp is short for Ampere, which is the standard International unit of current. An Amp is defined as the equivalent of 1 coulomb of charge in a conductor passing through a single cross-section of that conductor in one second

A Watt is the Standard International unit of power, (energy created or dissipated) at one Joule per second. In electrical terms, it is the equivalent energy created or dissipated by a voltage of 1V passing current through a conductor at 1A. (Power in Watts = Amps x Volts)

DC is short for Direct Current, and indicates that the current in the circuit flows in one direction only.

AC is short for Alternating Current, and indicates that current in a circuit flows in alternating directions in regular cycles.

A variable DC Power Supply is a device which converts a DC or AC input into a DC output, the current and/or voltage of which can be adjusted either manually or remotely.

A Variable DC Load is a device which draws current from a DC Power Supply (or battery). Commonly used for test and measurement purposes to ensure that power supplies can handle varying loads during operation (For example the power supply in a television will use say 15W in standby and 500W in use with a built in DVD). Intepro DC electrical loads can be programmed to a set current, voltage, power or resistance.

An AC source is similar to a DC Power Supply, where the output is an AC signal. In addition to being able to vary the AC voltage and current output, the Frequency of the signal can be altered to suit requirements.

AC voltage varies between a maximum positive at one half cycle, then to a maximum negative in the next half cycle about 0V. Generally this is in a sine wave, and the nominal value quoted is the Root Mean Square value. It is equivalent to the maximum peak value of one half cycle divided by √2 (1.414).

The SI define 1 Amp as a measure of current equivalent to one coulomb of electrical charge in a conductor going past a given point per second.

RMS stands for Root Mean Square. For alternating electric current, RMS is equivalent to the constant direct current that would produce the same power dissipation in a resistive load. As voltage is directly proportional to the current in a resistive load, the RMS voltage is the equivalent DC voltage that would provide the same power dissipation in a resistive load. It is calculated by dividing the peak voltage of one half cycle of the signal by 1.414 (√2). RMS voltage is also called the nominal AC voltage, for example 115V/230V mains are 115Vrms and 230V rms respectively.