Letter R

Random Access Memory (RAM)
Usually refers to a type of semiconductor memory often used
for temporary storage. RAM requires the continual application
of power to retain information. For some systems, battery
backup is used to prevent data or program loss in the event of a
power outage.

Reactance
The opposition to alternating current resulting from circuit
inductance and capacitance. The symbol for reactance is “X.”
The unit for reactance is the ohm.

Reactive Power
Power associated with inductance or capacitance. The unit for
reactive power is the var.


Read Only Memory (ROM)
Usually refers to a type of semiconductor memory often used
for permanent storage of data or programs that do not change.


Rectifier
A device or circuit that converts alternating current to direct
current.