What is the resistance of the ammeter and voltmeter?
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Solution
Resistance of ammeter
An ammeter is a device that is used to detect and measure the current flowing through a conductor. It is connected in series with the element along which the current needs to be measured.
For ammeters, the current must flow through it for measurement.
If an ammeter is connected in a parallel connection, then the incoming current will diverge into two branches. This will cause the measurement of the current to be lower than what it should be.
Resistance of voltmeter.
A voltmeter is a device that is used to measure the potential difference between two points and hence is connected parallel to the element across which the voltage needs to be measured.
A voltmeter will not be able to measure the potential difference if it is connected in series with the circuit as the entire current will be flowing through it and the voltmeter will just be acting as a resistance.
A minimal amount of current should flow through voltmeters in order to avoid errors in measurement.
Hence, the resistance of an ammeter must be ideally zero and the resistance of a voltmeter must be ideally infinitely large.
