Resonance in a series LCR circuit using 120 v.a.c.

Resonance in a series LCR circuit using 120 VAC. This is a series LRC circuit. 0-120 V.A.C. is supplied with a Variac. The light bulbs are the resistance; the large coil is the inductance, and the capacitance is a bank of capacitors in parallel. Resistance can be changed by removing or adding light bulbs. The inductance of the coil can be changed by moving a laminated iron core into or out of the center of the coil. Capacitance can be changed by throwing switches on the capacitor bank. A good set of values to start with is 25 micro f capacitance, and four 100 watt bulbs. When the variac is turned to 120 volts a.c., the bulbs glows dimly. When the laminated iron core is inserted half-way into the coil, the lamps glow brightly (LCR resonance). When the core is fully inserted, the lamps glows dimly again. ELECTROMAGNETIC OSCILLATIONS.