Effective Mass: The mass of a body which is being acted upon by the buoyant forces of air. The effective mass of a weight is its true mass minus the buoyant force of air displaced by the weight.

Effective Value (RMS): The alternating current value that will produce the same amount of heat in a resistance as the corresponding direct current value.

Efficiency: The ration of useful output energy, usually expressed as a percentage.

Effluent: Liquid that has passed through a processing operation.

Elastic Element: The material of which the transducer is constructed, generally selected for its good elastic properties.

Electrical Relay: Employs a solenoid to provide mechanical action to move a varying number of electrical contacts back and forth or on and off.

Electronic Switch: An electric circuit designed to cause a start and stop action or a switching action.

Electrostatic Field: The region surrounding an electric charge in which another charge experiences a force.

Element: A quality of product, material, or service forming a cohesive entity on which a measurement or observation may be made.

Empirical: Based on actual measurement, observation, or experience without regard to science and theory.

Endoergic Reaction: A reaction which absorbs energy.

ERG: A CGS unit of work or energy.

Error (of measurement): The result of a measurement minus the true value of the measurnand.

Exoergic Reaction: The reaction which liberates energy.

Explosion-Proof (XPRF) Motor: A totally enclosed motor that will withstand an explosion of a specific vapor or gas within its housing, or will prevent sparks or flashes generated within its housing from igniting surrounding vapor or gas.