Abbreviation of Volatile Organic Compound.
Abbreviation of Voice Coder.
Voice Coder
A device which converts speech input into coded form (usually digital) for secure transmission.
Voice Coil
Coil attached to the diaphragm of a moving coil loudspeaker.
Space between particles or material.
A solid or liquid material that easily vaporizes. A material with a significant vapour pressure.
Volatile Memory
A type of memory that loses the numbers stored in it when electrical power is removed from it.
Volatile Organic Compound
Organic chemicals and petrochemicals that emit vapours.
Volcanic Ash
Lava from a volcano that is in the form of chunks smaller than an apple, about the size of marbles.
Volcanic Bomb
A large lump of lava thrown out of a volcano during an eruption.
Volcanic Dust
Lava in the form of small, tiny particles thrown from a volcano during an eruption.
Volcanic Explosivity Index
A measure of the severity of a volcanic eruption.
Vents or fissures in the earth's crust through which gases, molten rock, or lava , and solid fragments are discharged.


Naturally occurring seven-carbon sugar alcohol. It is a substance widely distributed in plants, red algae, fungi, mosses, and lichens.

The volt is the SI unit of electromotive force.
Volt Amperes Reactive
Unit used to measure reactive power in an AC electric power system.
Volta, Alessandro, Count (1745-1827)
He invented the first practical battery using cells made from two kinds of metals; this verified his theory of differing electrical potentials for unlike metals.
A potential difference causes current to flow in a circuit, no voltage no current.
Voltage Amplifier
An amplifier in which the output-signal voltage is greater than the input-signal voltage.
Voltage Controlled Crystal Oscillator
A crystal-based oscillator whose center frequency can be varied with an applied voltage.
Voltage Diode Detector
The semiconductor diode in series with the input voltage and the load impedance.
Voltage Divider
A precision resistor network that reduces the output voltage of a device.
Voltage Doubler
A power-supply circuit so designed that the rectified voltage amplitude is doubled at the output.
Voltage Drop
Voltage or difference in potential developed across a component due to current flow.
Voltage Gain
Ratio of amplifier output voltage to input voltage usually expressed in decibels.
Voltage Multiplier
Rectifier circuit using diodes and capacitors to produce a DC output voltage that is some multiple of the peak value of AC input voltage.
Voltage Regulation
A measure of the ability of a generator or power supply to maintain a constant output voltage from no-load to full-load operation.
Voltage Regulator
A device or design implementation which regulates the electromotive force.
Voltage Standing Wave Ratio
In a waveguide, the ratio of the electric field (voltage) at a maximum point to that of an adjacent minimum point.
Voltage to Frequency Converter
A device that converts an analogue input voltage into a sequence of digital pulses with a frequency that is proportional to the input voltage.
Voltaic Cell
Or more commonly known as a battery.
Voltaic Efficiency
The battery discharge voltage divided by the charge voltage.
Voltaic Pile
An early battery consisting of disks of dissimilar metals (usually zinc and copper) separated by moist paper or cloth soaked in an electrolyte solution.
The amount of apparent power in an electrical circuit, equal to the product of voltage and current.
Voltampere (VA)
The product of rms voltage and rms current in an electronic circuit. It is the unit of apparent power in the International System of Units (SI).
A device for measuring voltage across a component in a circuit.
There are a number of derived units of volume in the British system of units and the SI system of units.
Volume Percentage
The concentration of a component in a mixture or an element in a compound.
Volume Thermal Expansion
Relative change in volume due to temperature change.
Volume Velocity
Within acoustics the volume velocity U of a source is the pressure p divided by the acoustic impedance Z.
Volumetric Efficiency
Ratio of the volume discharged from a pump to the piston displacement of the pump.
Volumetric Energy Density
Volume based energy density.
Volute Casing
Spiral shaped casing surrounding the pump or fan impeller that converts velocity energy to pressure energy.
Any flow possessing vorticity.
Vortex Shedding
A phenomenon which can occur when a fluid flows past a flexible structure.
A vector measure of local rotation in a fluid flow, defined mathematically as the curl of the velocity vector.
Vorticity Equation
A dynamic equation for the rate of change of the vorticity of a parcel, obtained by taking the curl of the vector equation of motion.
The trapezoidal stones that are often used to form a rounded arch.
Voice operated Switch.
Voyager Probes
Space probes launched by NASA in 1977. Their official missions were to study Jupiter and Saturn, but the probes were able to continue on.