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Electrical Science Volume 4 of 4 | Next
Ammeter |
AMMETERS
Test Instruments & Measuring Devices
AMMETERS
Measurement of current being supplied to or from a component is measured by
an ammeter.
EO 1.2
STATE the electrical parameters measured by each of
the following in-place measuring devices:
b.
Ammeter
EO 1.3
EXPLAIN how the following electrical test equipment
and measuring devices are connected to a circuit:
b.
Ammeter
Ammeter
The ammeter measures electric current. It may be calibrated in amperes, milliamperes, or
microamperes. In order to measure current, the ammeter must be placed in series with the circuit
to be tested (Figure 6).
When an ammeter is placed in series with a circuit, it will increase the resistance of that circuit
Figure 6 Ammeter
by an amount equal to the internal resistance of the meter Rm. Equation (14-3) is the
mathematical representation of the current without the meter installed.
(14-3)
Io
V
Ro
ES-14
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