# Resources

## How to use this resource

Below are a series of interactives which support the resource. Each interactive can be launched by clicking on its image, or through links in the PDF itself.

Some resources have pre-requisites; where this is the case, you'll be able to access any required resources through the Pre-requisites section.

## Topic areas

### Electrical and electronic engineering

• AC true, reactive and apparent power
• AC power factor

### Mathematics

• Pythagoras’ theorem
• Trigonometry

## Pre-requisites

‘AC phasors and fault detection’ resource to introduce phasor diagrams and the relationship between resistance, reactance and impedance.

## Problem statement

The relationship between voltage and current in an AC system is determined by the impedance of the circuit.

The impedance can consist of a resistive component and a reactive component, the latter of which introduces a
phase difference between voltage and current.

How does the phase difference affect the power drawn by the circuit (in this case a motor)?

## Interactives

### Click the image to load LCR Series 1. The above interactive allows you to change the frequency, resistance, inductance or capacitance, and displays the appropriate impedance effect or supply voltage needed.

### Click the image to load LCR Series 2. The above interactive allows you to change the frequency, resistance, inductance or capacitance, and displays the relevant true, apparent and reactive powers.

#### Supported by

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