Lesson Notes By Weeks and Term v5 - Grade 8

Lesson Video

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Performance objectives

• Differentiate between series and parallel circuits.
• Describe how current and voltage behave in each.
• Explain the function of different switches.
• Draw circuit diagrams for series and parallel circuits.
• Build and test simple circuits.

Lesson summary

This week, we delve into the fascinating world of more complex electrical circuits and switches. Building on what we learned about simple circuits (single bulb, single switch), we’ll explore how to combine components to create circuits that can do more, like controlling multiple lights from different locations or powering different appliances at varying intensities. Understanding these concepts is crucial in South Africa because electrical systems are fundamental to our daily lives, from powering our homes and schools to running industries and providing essential services.

Lesson notes

2.1 Series Circuits In a series circuit, components are connected one after another along a single path. Think of it like a single-lane road – all the cars (electrons) must follow the same route.

Current (I): The current is the same at all points in a series circuit. Because there is only one path, the rate of electron flow is consistent throughout. Imagine the number of cars passing any point on our single-lane road is the same.

Voltage (V): The total voltage supplied by the battery is divided among the components in the circuit. Each component "uses up" some of the voltage. It's like the total distance of a journey being split between different towns along the way. If you have two bulbs in series, each bulb will receive less voltage than the battery supplies.

Resistance (R): The total resistance in a series circuit is the sum of the individual resistances of each component. R total = R 1 + R 2 + R 3 + ...

Effect of adding components: Adding more components (e.g., bulbs) in series increases the total resistance. This decreases the current flowing through the circuit, and each bulb will become dimmer. If one bulb blows in a series circuit, the entire circuit is broken (like a roadblock!), and all the other bulbs will go out.