Question

How does an ammeter, a voltmeter, and an ohmmeter work. Shunt resistance, etc.

Answer 1

Ammeter and Voltmeter = A voltmeter and ammeter are instruments used by electrical engineers to diagnose and troubleshoot electrical circuits.
An ideal voltmeter has two terminals and senses the voltage between the terminals where they may be connected to a circuit. Ideally the voltmeter has infinite resistance. It is polarized and indicates polarity as well as the magnitude of the voltage.
An ideal ammeter is a two terminal device, also polarized. It is connected in series with circuit elements to measure the sign and magnitude of the current flowing through that component. The circuit has to be opened to insert the ammeter to measure current flow. The ideal ammeter has no resistance to flow.

Ohmmeter = In an Ohmmeter, the deflection of the needle is controlled by the amount of battery current. Before calculating the resistance of an unknown electrical circuit or resistor, first of all, the test leads of the Ohmmeter are shorted together. When the leads are shorted, the meter is adjusted for proper operation on the selected range and the needle drives back to the maximum position on the Ohms scale and the meter current is max. After using an Ohmmeter, the test leads should be removed. If the test leads remain connected to the Ohmmeter, then the battery of the meter gets discharged. When the rheostat is adjusted properly, with the test leads shorted, the needle of the meter comes to zero position, and this specifies a zero resistance between the test leads.

Shunt Resistance = A resistor having a very low value of resistance connected in parallel with other resistor such type of resistor is called shunt resistance.

The ammeter measuring range can be extended by connecting shunt resistance to it.

It also acts as path diverter by allowing electric current to pass around another point in the circuit by creating a low resistance path.

hope it helps! : )