Three characteristics define an electrical circuit: resistance, inductance and capacitance.

Resistance, a characteristic conferred by the components of the same name, reveals the places where these components cause the current to rise. When the voltage, the power supply, is fixed, the current required varies with the resistance – more resistance, more current. The more the circuit “resists”, the more current it consumes.

Inductance, on the other hand, is caused by the coils that make up the circuits. They are nothing more than wire coils, which, when passed through alternating current, the kind in sockets, generate a magnetic field around them, just as, if they are exposed to a magnetic field, they generate current.

Finally, we have Capacitance, linked to capacitors, a kind of small battery in which energy is stored. Once again, unlike what happens with direct current, which is supplied to us in small devices and for small devices, such as cell phone transformers, ordinary batteries, or even our car battery, it is with alternating current, that of the sockets, where the most interesting thing happens again, and our capacitor is transformed from a simple wire into a complex and effective filter.

Let’s just look at the latter, since resistance behaves in the same way in direct and alternating current, i.e. in both small and domestic and large and public applications. So that they can be compared to the former and thus design circuits, resistivity values have been imagined for capacitance and inductance. And this is where we find its greatest interest: when the value of the resistivity of the inductance is equal to that of the resistivity of the capacitance, the circuit goes into resonance. It is this resonance, which occurs at a certain frequency, that allows us to tune in to a radio or television channel – so we can say that it is resonance that promotes communication and allows us to capture what is everywhere but not visible, such as the airwaves that transmit your sound as well as your image.

No matter how much or how little we resist, it’s when our Capacity matches our Induction permeability that we tune in and allow clear, noise-free communication. Unlike the direct or domestic current, the alternating current is of/for everyone and it is common to us.

It is in this commonality that we tune in, since in the domestic one there is no noise at all.

No matter how little you resist.

João Chaves