The ease of changing the amplitude of an AC voltage compared to changing its frequency is primarily due to the nature of the electrical components used in AC circuits.
AC voltage can be easily modified using transformers. Transformers are designed to efficiently transfer electrical energy from one circuit to another by electromagnetic induction. They consist of two or more coils of wire wrapped around a magnetic core. By varying the number of turns in the coils, transformers can step up or step down the voltage level of an AC signal while maintaining its frequency.
For example, a step-up transformer increases the voltage by having more turns in the secondary coil than in the primary coil. Conversely, a step-down transformer reduces the voltage by having fewer turns in the secondary coil.
In contrast, changing the frequency of an AC voltage is more challenging because it involves altering the rate at which the alternating current oscillates. The frequency of an AC signal is determined by the source generating the signal, such as a power plant or an electronic oscillator.
To modify the frequency of an AC voltage, specialized devices like frequency converters or variable frequency drives (VFDs) are used. These devices typically employ complex electronic circuits that involve conversion techniques, such as rectification, inversion, and modulation. While they can change the frequency of the AC voltage, the process is more intricate and typically requires advanced electronic components and control systems.
In summary, changing the amplitude of an AC voltage is relatively straightforward and can be achieved using transformers, whereas modifying the frequency is more complex and typically involves specialized devices and sophisticated control techniques.