Figure 1-1.
Connection of an ammeter in a circuit
a. You must observe polarity when connecting an ammeter into an electrical
circuit. To do this properly, you must trace electron flow from the negative (-)
side of the battery through the circuit and back to the positive (+) side of the
battery.
b. Then break the circuit and connect the ammeter so that electrons enter the
negative side and exit through the positive side into the load (fig. 1-1b).
c. An ammeter that measures smaller amounts of current is called either a
milliammeter or a microammeter, depending upon the amounts of current to be
measured.
3.
The electrical instrument used to measure difference of
potential, or voltage, is a voltmeter.
It is connected so it measures the
difference of potential between two points.
Figure 1-2b illustrates the proper
connection of a voltmeter.
a. To measure the electromotive force of the battery, you must connect
voltmeter V1 (fig 1-2b), while observing polarity.
To measure the potential
difference between points X and Y of the circuit (fig 1-2a), it is necessary to
trace the electron flow and observe the polarity between points X and Y.
b. Note that the side of the resistor that the electrons enter
is
the
negative side. A meter that is connected across a difference of potential
(fig 1-2b), is in parallel.
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