UNIT OVERVIEW

Every time you switch on a light, charge your phone, or start a car, you use the principles covered in this unit. You will learn how real batteries behave (they are not perfect!) and how to analyse circuits that combine series and parallel connections.

You already know Ohm's Law and basic circuit analysis from earlier grades. Now you will understand why batteries "run out" of power, why old phone batteries charge slower, and how to solve circuits that look complex but follow logical rules.

By the end of this unit, you will be able to:

• Explain the difference between EMF and terminal potential difference
• Calculate the internal resistance of a battery and predict its effect on circuit performance
• Analyse series-parallel networks with confidence
• Calculate equivalent resistance, current, and voltage in multi-component circuits
• Conduct an experiment to measure internal resistance
• Apply these concepts to real-world electrical problems

Real-life applications:

1. Why your car struggles to start in cold weather — Battery internal resistance increases at low temperatures
2. Voltage drops during load-shedding — Understanding why appliances may not work properly
3. Solar panel systems — Calculating how to connect panels and batteries efficiently
4. Smartphone battery degradation — Why older batteries cannot deliver the same current as new ones

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