# Module 10 − LCR Parallel Circuits

### What you'll learn in Module 10.

- Module 10.1 Ideal Parallel Circuits.
- • Recognise ideal LCR parallel circuits and describe the effects of internal resistance.
- Module 10.2 Practical Parallel Circuits.
- • Describe the action of practical LCR parallel circuits with the use of phasor diagrams.
- Module 10.3 Parallel Resonance.
- • Describe the action of LCR parallel circuits above, below and at resonance.
- • Describe current magnification, and dynamic resistance in LCR parallel circuits.
- • Use appropriate formulae to carry out calculations on LCR parallel circuits, involving resonance, impedance and dynamic resistance.
- Module 10.4 Damping.
- • Describe methods of damping in LCR parallel circuits, and relate Q factor and bandwidth.
- Module 10.5 Parallel Circuits Quiz.
- • LCR Parallel Circuits Quiz.

### The LCR Parallel Circuit.

In introducing the LCR Series Circuit, one of the most useful combinations of "passive components" in electronics, Module 9 set the groundwork for Module 10. If the LCR series circuit is just one of the most useful circuits, here is the other one, the **LCR Parallel Circuit!**

The parallel LCR circuit uses the same components as the series version, its resonant frequency can be calculated in the same way, with the same formula, but just changing the arrangement of the three components from a series to a parallel connection creates some amazing transformations. Almost everything about the series circuit is turned upside down by the parallel circuit. As you read through this module, notice how many opposites there are between series and parallel circuits. It is because of these opposite effects, that series and parallel resonant circuits can together perform very many more important tasks in analogue electronics.