LESSON 1
POTENTIOMETRIC METER PRINCIPLES
TASK
Describe and identify theory and terminology used in the application of
potentiometric meters.
CONDITIONS
Given information and illustrations about theory and terminology relating to
the application of potentiometric meters.
STANDARDS
Demonstrate competency of the task skills and knowledge by correctly
responding to 75 percent of the multiple-choice test covering theory and
terminology of potentiometric meters.
REFERENCES
None
Learning Event 1:
DESCRIBE THE POTENTIOMETER AND ITS APPLICATION
1.
The laboratory potentiometer described here is a precision-measuring
instrument; it is not an electrical component and should not be confused
with the three-terminal variable resistor, which is also referred to as a
potentiometer.
It acts to compare directly and accurately, through null
output indication, unknown DC voltages with reference-derived voltages. It
is unlike the instrument bridge, which (by nulling techniques) makes
accurate comparisons of impedances, one of which is the standard or
reference component. Similar to bridge instruments, most potentiometers are
designed for precision laboratory use and most often obtain comparisons by
2.
For reference and standardization, the potentiometer requires the
stable precise voltage delivered by a standard cell or zener diode voltage
source plus the ratios obtained from precisely and accurately calibrated,
fixed and variable resistors. The bridge, on the other hand, derives its
accuracy from reference to an accurate resistance standard.
3.
The potentiometer is limited in basic voltage range by the standard
cell, so it must be used with resistance ratio devices for extension to
other voltage ranges. Its chief advantage lies in direct applicability to
voltage-related devices in the measurement of current and resistance.
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