AC2 Fundamentals Unit 3 – Parallel Resonance
Exercise 1 – Parallel Resonant Circuits
EXERCISE OBJECTIVE
When you have completed this exercise, you will be able to compute the resonant frequency,
total circuit current, and impedance of a parallel LC circuit by using standard electronics
formulas. You will verify your results with an oscilloscope.
DISCUSSION
- At the resonance frequency, inductive and capacitive reactance are equal in a parallel LC
tank circuit. - The equation fr = 1/[2π(sqrt(LC))], is used to calculate the resonant frequency for both
parallel and series resonant circuits. - At resonance, an LC tank circuit has a very high impedance and exhibits resistive
characteristics. - Ohm’s law is used to determine total line current, which, at resonance, is minimal.
- Voltage (VRESON) across the tank circuit, at resonance, is maximal.
- At resonance, the reactive components are equal and opposite therefore canceling one
another. - The applied voltage and total current are in phase when the circuit is at resonance.