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Electric
Meters |
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Electric Meters
Electric meters are
instruments used to measure electrical values. Two common meters are the
ammeter and the voltmeter, both of which are variations of the
galvanometer. A small magnet inside a galvanometer sets up a magnetic
field, generating a measurable force when current flows through a nearby
coil. The meter mechanisms are shown here schematically. The ammeter
diverts electricity through a coil via a shunt (illustrated beneath the
device), measuring the amount of current flowing through the circuit in
amperes. It is connected in series, or directly in the line of the
circuit. The voltmeter is connected in parallel, so that the lightbulb
falls between its two connections into the circuit. It is designed to
measure potential differences. To ensure that it removes a minimum of
current from the circuit, the voltmeter's resistance (shown by the
jagged black line beneath the device) must be very high.
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