What are the two main classes of capacitors?

The two main classes of capacitors are indeed fixed and variable. Fixed capacitors have a predetermined capacitance value that does not change under normal operating conditions. These capacitors are widely used in various electronic circuits where stable and reliable capacitance is required, like in filtering applications or coupling/decoupling circuits.

Variable capacitors, on the other hand, have capacitance values that can be adjusted. They are often used in applications such as tuning radio frequencies or in circuits that require adjustable filtering.

This classification helps in understanding how capacitors are used in different electronic applications, laying the groundwork for more complex topics in electronics design and analysis. Understanding the distinction between fixed and variable capacitors is crucial for effectively selecting the right type of capacitor for a specific application.