E
Echo: To reflect received data to the sender. For
example, keys depressed on a keyboard are usually echoed
as characters displayed on the screen.
EEPROM: Electrically Eraseable Programmable
Read Only Memory.
Electrical Interference: Electrical noise induced
upon the signal wires that obscures the wanted information
signal.
Electrode Potential (E): The difference in potential
established between an electrode and a solution when
the electrode is immersed in the solution.
Electrolyte: Any substance which, when in solution
will conduct an electric current. Acids, bases, and
salts are common electrolytes.
Electromotive Force (emf): The potential difference
between the two electrodes in a cell. The cell emf is
the cell voltage measured when no current is flowing
through the cell. It can be measured by means of a pH
meter with high input impedance.
Electronic Industries Association (EIA): A standards
organization specializing in the electrical and functional
characteristics of interface equipment.
EMF: Electromotive force. A rise in (electrical)
potential energy. The principal unit is the volt.
EMI: Electromagnetic Interference (Emission).
Emissivity: The ratio of energy emitted by an
object to the energy emitted by a blackbody at the same
temperature. The emissivity of an object depends upon
its material and surface texture; a polished metal surface
can have an emissivity around 0.2 and a piece of wood
can have an emissivity around 0.95.
Encoding: The process of putting information
into digital format.
Encryption: A technique of modifying a bit stream
to make it appear to be a random sequence of bits to
someone who does not have access to the encryption scheme.
End Point (Potentiometric): The apparent equivalence
point of a titration at which a relatively large potential
change is observed.
End Points: The end points of a full scale calibration
curve.
Endothermic: Absorbs heat. A process is said
to be endothermic when it absorbs heat.
Enthalpy: The sum of the internal energy of
a body and the product of its volume multiplied by the
pressure.
Environmental Conditions: All conditions in
which a transducer may be exposed during shipping, storage,
handling, and operation.
Eprom: Erasable Programmable Read-Only Memory.
The PROM can be erased by ultraviolet light or electricity.
Equilibrium Constant: The product of the concentrations
(or activities) of the substances produced at equilibrium
in a chemical reaction divided by the product of concentrations
of the reacting substances, each concentration raised
to that power which is the coefficient of the substance
in the chemical equation.
Equivalent Conductance (l): Equivalent conductance
of an electrolyte is defined as the conductance of a
volume of solution containing one equivalent weight
of dissolved substances when placed between two parallel
electrodes 1 cm apart, and large enough to contain between
them all of the solution. l is never determined directly,
but is calculated from the specific conductance (Ls).
If C is the concentration of a solution in gram equivalents
per liter, then the concentration of a solution in gram
equivalents per liter, then the concentration per cubic
centimeter is C/1000, and the volume containing one
equivalent of the solute, is, therefore, 1000/C.
Equalization: Compensation for frequency dependent
attenuation in a comunications circuit.
Error Band: The allowable deviations to output
from a specific reference norm. Usually expressed as
a percentage of full scale.
Error: The difference between the value indicated
by the transducer and the true value of the measurand
being sensed. Usually expressed in percent of full scale
output.
Ethernet: A LAN standard, also known as IEE
802.3, that connects computers by means of coaxial cable
or twisted paid conductors.
Eutectic Temperature: The lowest possible melting
point of a mixture of alloys.
Excitation: The external application of electrical
voltage current applied to a transducer for normal operation.
Exothermic: Gives off heat. A process is said
to be exothermic when it releases heat.
Expansion Factor: Correction factor for the
change in density between two pressure measurement areas
in a constricted flow.
Explosion-proof Enclosure: An enclosure that
can withstand an explosion of gases within it and prevent
the explosion of gases surrounding it due to sparks,
flashes or the explosion of the container itself, and
maintain an external temperature which will not ignite
the surrounding gases.
Exposed Junction: A form of construction of
a thermocouple probe where the hot or measuring junction
protrudes beyond the sheath material so as to be fully
exposed to the medium being measured. This form of construction
usually gives the fastest response time.
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