Megger

El Voltímetro


Materiales:
1 Galvanómetro
1 Decade resistor box
1 Power supply
1 Voltimetro
6 connecting wires + alligator clipper


Objetivos:

1. Explicar el funcionamiento delGalvanómetro de D’Arsonval
2. Discutir el funcionamiento del voltímetro
3. Aplicar el principio de funcionamiento del galvanómetro para construir un voltímetro


Pre-Lab
Discuss theD’Arsonval Movement

[pic]
Fig.1: Inside of Galvanometer

http://www.tpub.com/content/neets/14188/css/14188_79.htm

  What component supplies restoring force to the coil of the D’Arsonval meter movement?A voltmeter is a device used to measure the voltage potential between two points in an electrical circuit. First created in the early 1800s, voltmeters were originally called galvanometers.Technically, all voltmeters are ammeters, as they measure current rather than voltage. Although current is measured in amps, Ohm's Law, which establishes the relationship between voltage, current andresistance, can be used to scale the amps to volts.

Because all measurable electrical properties are related to each other through Ohm's Law, in practice most voltmeters are actually multimeterscapable of measuring voltage, current and resistance. When measuring voltage, a large resistance is placed in line with the coil of the D'Arsonval movement to minimize interference with the circuit beingmeasured. This is also due to Ohm's Law, which states voltage is directly proportional to resistance. By minimizing the voltage consumed by the voltmeter itself, a more accurate measurement of thecircuit's voltage can be obtained. Current is inversely proportional to resistance; conversely, to minimize the amount of current flowing into an ammeter, a large resistance is placed in parallel withthe coil.

Modern multimeters come with digital displays and may even use digital measuring techniques rather than a D'Arsonval movement. By incorporating microprocessors, they are also capable...