5L20.26 • RLC Circuits AC: LC Circuit w/ Parallel Resonance

Location: Cabinet 3

Photo of the Demonstration at the University of Texas at Austin.

Instructions / Notes:

• The purpose of the demo is to show an example of a LC circuit that resonates only at a specific frequency.
• The demo makes good follow up to 5L20.10 RLC Phase Differences.
• The demo has a large primary coil powered by a function generator.
• A second coil/inductor is wired to a capacitor and a pair of light emitting diodes within its windings.
• To attain resonance in the secondary LC coil, the function generator must be adjusted to a frequency of 210 KHz.

• At resonance two red light emitting diodes will fully light up.

Further Notes:

• The secondary coil is removeable to show that no wired connections exist between the two coils.
• If needed. we offer a back-up secondary coil - which uses a different capacitor - and - unfortunately a different number of windings as the previous secondary coil.
• This second coil must be driven at a frequency of 360 KHz to attain resonance.

Last updated on June 8, 2026