A road or rail bridge of considerable length, usually carrying vehicles at an elevated height across a valley or round a mountain side, as opposed to simply across a specific obstacle.
Vibrating String
When a string vibrates it radiates as a dipole and is very inefficient and so needs to be attached to a panel that will be excited by the vibrations in the string and act as a far more efficient radiator of sound.
Vibrating Wire
A sensor that monitors pressure by measuring the change in resonant frequency of a pre-tensioned wire in response to pressure or force changes.
An oscillation about an equilibrium position or shape.
Vibration Dose Value
Defined as the 4th root of the time integral of the 4th power of the 1-32 Hz filtered acceleration.
Vibration Finishing
A surface finish achieved using a machine that vibrates a volume of abrasive material within which the item to be finished sits.
Vibration Finishing Machine
A machine that vibrates a volume of abrasive material within which the item to be finished sits.
Vibration Isolation
Vibration problems are solved by onsidering the system as a number of springs and masses with damping.
Vibration Isolator
A resilient support for vibrating equipment designed to reduce the amount of vibration transmitted to the other structures.
Vibration Severity
A criteria for predicting the hazard related to specific machine vibration levels.
Vibratory Bowl Feeder
Hopper or conveyor mechanism utilizing a vibratory motion.
A device for holding material securely whilst being cut, filed or machined in some way.
Vice Jaw Caps
Parts that fit over the steel jaws of a vice to protect the work.
Vice Jaw Inserts
Replaceable hardened steel inserts for vice jaws.
Vicker′s Hardness
Determined by indenting the material with a diamond pyramid under a specific load and then measuring the size of the impression.
The technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.
Video Amplifier
An amplifier designed to amplify the entire band of frequencies from 10Hz to 6MHz.
Video Graphics Array
An early colour graphics standard for PCs.
A television pickup tube utilizing a photoconductor as the sensing element.
A drawing of a side of an object.
View Factor
The fraction of the total energy emitted by one surface that is directly incident on another surface.
Related to intervals of 20.
The gradual reduction of image illuminance with an increasing off-axis angle, resulting from limitations of the clear apertures of elements within an optical system.
Villari Effect
The change in magnetic properties of a ferromagnetic material in response to the presence of stress in the ferromagnetic material.
The horizontal bar in a fraction separating the numerator from the denominator.
Vinyl Acetate


A colourless liquid with a pungent odor, it is the precursor to polyvinyl acetate, an important polymer in industry.

Vinyl Benzene
Another name for Styrene.
Alternative name for Acrylonitrile.
Another name for 1,3-Butadiene.
Vinylformic Acid
Alternative name for Acrylic Acid.
Viral Vector
A viral DNA altered so that it can act as a vector for recombinant DNA.
An alloy with 81% Copper, 10% Zinc and 9% Nickel. A German Silver type of alloy containing nickel as well as copper and zinc with a magnetic element as a built in security device.

Streaks or wisps of precipitation, such as water or ice particles, that fall from clouds but evaporate before reaching the ground.
Virgin Metal
Primary metal obtained directly from ores rather than recycled scrap.
A single virus particle.
Virtual Ground
A point in a circuit that is at ground potential but is not connected to ground.
Virtual Image
The image formed when light only appears to come from the location of the image.
Virtual Instrumentation
A layer of software and/or hardware added to a general-purpose computer in such a fashion that users can interact with the computer as though it was their own custom-designed traditional electronic instrument.
Virtual Mass
The actual mass of a body, plus its apparent additional mass.
Virtual Particles
Particles that exist only for the brief moment allowed by Heisenberg′s uncertainty principle.
A small microbe. Viruses cause diseases such as the common cold, flu, polio and smallpox.
A type of deformation exhibiting the mechanical characteristics of viscous flow and elastic deformation.
A measure of the internal friction within a fluid.
Viscosity Grade
Any of a number of systems which characterize lubricants according to viscosity for particular applications.
Viscosity Index
An arbitrary measure for the change of kinematic viscosity with temperature.
Viscosity Index Improvers
Additives that increase the viscosity of the fluid throughout its useful temperature range.
Viscosity Modifier
Lubricant additive, usually a high molecular weight polymer, that reduces the tendency of an oil′s viscosity to change with temperature.
Possessing viscosity. Frequently used to imply high viscosity.
Viscous Coupled Differential
Limited slip device which uses sheared fluid between two plates to limit wheelspin.
Viscous Damping
Viscous damping is the dissipation of energy that occurs when a particle in a vibrating system is resisted by a force proportional to the velocity of the particle.
Viscous Flow
The flow of fluid through a duct under conditions such that the mean free path is very small in comparison with the smallest dimension of a transverse section of the duct.
Viscous Fluid
A fluid whose molecular viscosity is sufficiently large to make the viscous forces a significant part of the total force field in the fluid.
Viscous Force
The force per unit volume or per unit mass arising from the action of tangential stresses in a moving viscous fluid.
Viscous Stresses
The components of the stress tensor when the pressure, i.e., the mean of the three normal stresses, has been subtracted out from each of the normal stresses.
Viseoelastic Material
A material which can behave as an elastic solid on a short-time scale and as a viscous fluid on a long-time scale.
Visible Light
Visible light is electromagnetic radiation with a wavelength between 400 and 750 nm.
Visual Colour
Also known as perceived colour is the quality of light emission as conveyed by the human eye, combining the impressions of 3 types of light-sensitive cells which the eye contains.
Vital Air
An old name for oxygen
Vital Heat
A term that has generally referred to the heat produced within the body, usually the heat produced by the heart and the circulatory system.
A substance that is critical for proper functioning of a living organism that the organism is unable to produce in sufficient quantities for itself.
Vitiated Air
Air from which oxygen has been removed, thus mainly nitrogen.
Vitreous Enamel
An opaque or transparent glaze, generally coloured, which adheres to a suitable metallic surface when applied in a liquid state.
Vitreous Silica
The glassy isotropic form of quartz.
During firing of a ceramic body, the formation of a liquid phase that becomes a glass-bonding matrix upon cooling.
Vitrifying Tendency
Tendency of the crystalline phase of a ceramic to transform into an amorphous or glassy phase when subjected to aging or temperature cycling.