UEEEL0039 Design, install and verify compliance and functionality of general electrical installations (CAPSTONE)

a property of a circuit component, instrument or some other device which encapsulates the relationship between the potential difference (PD) across the device and the current through it. For steady (constant) PD and current, the impedance is equivalent to the resistance, the quotient of PD divided by current, but if the PD and current vary with time, you have to take into account the fact that there may be some delay between cause and effect - potential differences and currents may not change in unison. To specify impedance in such cases you have to know, as well as resistance, a second property called reactance which depends on the relationship among PD, current and the time scale of the changes. The two properties, resistance and reactance, together constitute impedance which cannot be described by a single numerical value. In DC circuits - with steady currents - the reactance of all components can be ignored, so in those cases impedance means the same as resistance. Some folks, such as loudspeaker salespersons, say impedance when they mean resistance.

Source: http://www.physics.usyd.edu.au/teach_res/db/elgloss.htm

The effect that inductors have to changing current.

The influence that the magnetic field has on the current in a coil.

Opposition to current flow caused by a coil when an AC supply is used.

An inductor is a coil of wire. 

The INSTANTANEOUS value of an alternating voltage or current is the value of voltage or current at one particular instant.

Voltage drop due to current and resistance.

Separate from supply

Type of transformer used to separate a supply with respect to ground.