500-turn coil, 2-uF capacitor, 2-volt light bulb, and F.G. are connected in series. As you vary the frequency, the light bulb glows brightly at resonant frequency about 509Hz (w/iron core) or 1,047Hz (w/o iron core). Use display meter you can show the sum of the pd cross inductor and capacitor is much greater than the source voltage (at the resonant frequency). Oscilloscope is a optional to monitor the signals.