## Glossary V

Following is a definition of terms frequently used in the instrumentation, industrial automation and test & measurement communities.

**Vacuum:** Any pressure less than atmospheric pressure.

**Velocity:** The time rate of change of displacement; dx/dt.

**Vibration Error Band:** The error recorded in output of a transducer when subjected to a given set of amplitudes and frequencies.

**Vibration Error:** The maximum change in output of a transducer when a specific amplitude and range of frequencies are applied to a specific axis at room temperature.

**Viscosity:** The inherent resistance of a substance to flow.

**Volt:** The (electrical) potential difference between two points in a circuit. The fundamental unit is derived as work per unit charge-(V = W/Q). One volt is the potential difference required to move one coulomb of charge between two points in a circuit while using one joule of energy.

**Voltage**: An electrical potential which can be measured in volts.

**Voltmeter**: An instrument used to measure voltage.

**Volume Flow Rate:** Calculated using the area of the full closed conduit and the average fluid velocity in the form, Q = V x A, to arrive at the total volume quantity of flow. Q = volumetric flowrate, V = average fluid velocity, and A = cross sectional area of the pipe.