In recent experiments, you found out that the voltages in a loop add up to zero. A voltage therefore only applies to your voltmeter, if it is located in a loop. This is a direct consequence of the Kirchhoff's Voltage Law. Therefore...
To measure voltage, the voltmeter must be connected in parallel to the voltage to be measured!
In order not to influence the measurement results, an ideal voltmeter has infinite internal resistance.
In the next experiment, you introduce a capacitor into the circuit...