UHF
It is an abbreviation for "ultra high frequency."

Ultrasonic
Signals of high frequency range which is beyond human hearing. It is approximately 20 kHz.

Unijunction Transistor
It is device with three terminals acting as a diode with its own internal voltage divider biasing circuit.

VA
It is an abbreviation for "volt ampere."

Vacuum Tube
Also known as "Vacuum Valves." It is an electron tube from where all air and gas has been evacuated. It was previously used in radio and electronics.

Vector
It is a quantity, usually represented by a line, have both magnitude and direction. The length of the line indicates magnitude and orientation, the direction.

Vector Diagram
It is an agreement of vectors which shows the phase relationships between two or more AC quantities in the same frequency.

Very high frequency (VHF)
It is a radio frequency band from 30 MHz (wavelength 10m) to 300 MHz (wavelength 1m).

Very low frequency (VLF)
It is a radio frequency band from 3 kHz to 30 kHz.

Volt
It is the unit of measurement of electromotive force causing the flow of one ampere of current in a circuit of a resistance of one ohm. It is symbolized by "V." The word "volt" has been named after an Italian physicist of the 18th century, Alessandro Volta.

Voltage
It is a term used for the electromotive pressure or force that exists across a voltage source or a load in a circuit. It is measured in volt.

Voltage Amplifier
It is an amplifier designed to maximise voltage gain. Also see "amplifier."

Voltage Multiplier
It is a rectifier circuit which uses diodes and capacitors inorder to produce a DC output voltage, being the multiple of the peak value of AC input voltage. This process is cost effective. Example : Voltage doublers and voltage triplers.

Voltage Regulator
It is a device or a circuit which helps in maintaining constant output voltage from varying voltage and/or load current.

Voltage Source
A device or a circuit supplying voltage to a load.

Voltaic Cell
It is a primary cell containing solution and a pair of unlike electrodes immersed in it for the purpose of chemical interaction, and further producing voltage.

Voltmeter
It is an instrument used in measuring the difference in potential between two points.