The negative side of a cap depends on the type of capacitor. There are polarized capacitors and non-polarized capacitors, which have different ways of determining polarity.

On the other hand, non-polarized capacitors, such as ceramic capacitors and film capacitors, do not have a distinguishable negative side. They can be connected in any orientation without regard to polarity. This makes them more versatile and easier to use in circuits where polarity may be unpredictable or changing.

In conclusion, the negative side of a cap is a crucial factor to consider when using polarized capacitors in electrical circuits. It is important to pay close attention to the markings on the capacitor body to ensure proper polarity and avoid potential damage. However, non-polarized capacitors offer greater flexibility and can be connected without regard to polarity, making them a more convenient option in some situations. Ultimately, the choice of capacitor type and polarity should be based on the specific needs and requirements of the circuit being designed.