Determining the impedance in circuits with capacitors and coils - Measuring with Mobile-CASSY

The experiment P3.6.3.6 examines the oscillator circuit as the series and parallel connection of capacitance and inductance. The total impedance of the series circuit

disappears at the resonance frequency

i.e. at a given current I the total voltage U at the capacitor and the coil is zero, because the individual voltages U_C and U_L are equal and opposite. For parallel connection, we can say

At the resonance frequency, the impedance of this circuit is infinitely great; in other words, at a given voltage U the total current I in the  supply line is zero, as the two individual currents I_C and I_L are equal and opposed.