Question

Why is a voltmeter connected in parallel cross a conductor in a circuit? If by mistake a voltmeter is connected in series in a circuit, what will happen?

Answer 1

Voltmeter ideally have infinite internal resistance, practically a large enough resistance. So if connected in series, a very small current will flow or no current will flow. ... Since no current flowing, voltmeter will show the voltage of battery connected across.

Answer 2

As voltmeter has infinite resistance and to measure potential difference you have to connect it parallel always .