Basic laws and concepts in electronics: part 1 – In order to understand the phenomena taking place in the world of electronics, it is necessary to acquaint and learn fundamental laws and concepts related to it, such as the Current, Voltage, Power, Resistance, Ohm’s law and Kirchhoff’s laws. We will try as good as we can to explain “from the beginning”, in our opinion the most important topics such as:

1. Electronic components.

2. Electrical circuits.

In the second part of this article, we will mention topics such as:

1. Electric charge.

2. Electric Voltage, Electric Current, Electric Power, Resistance.

3. Ohm’s Law, Kirchhoff’s Laws.

1. Electronic components – electrical components that have the ability to generate electrical energy (at the expense of other types of energy), energy storage and energy dissipation. These components can be divided into:

• Active electronic components – this group contains components that can generate energy in the elecrronic circuit or change their parameters, but they also require being supplied by external power sources These components are e.g. diodes, transistors, tunnel diodes, electronic chips (integrated circuits).

Active electronic components

• Passive electronic components – they do not generate energy on their own, but can store it or dissipate it (e.g. resistors, capacitors, inductors).

Passive electronic components

2. Electrical circuit – a group (smaller or larger) of electronic components connected together by wires or conductive paths and forming a closed path for electric current, called circuit. The electric current in the circuit always chooses the path of the least resistance and flows through the wire or path always from the “positive” to the “negative” terminal. Remember, that electrons flow in the opposite direction. Circuits can be suited either for Direct Current (DC) operation or Alternating Current (AC) operation, which is determined by the time dependency of the current from the time I(t). We also distinguish two ways of connecting electronic components together in the circuit and these are so-called:

• Series circuits – the end of the first component is connected to the beginning of the next one (in-line with the power source, like in the picture below). The current in the ideal circuit will have the same value in every point of the circuit and the voltage across the ideal circuit equals the sum of the voltage drops across all of the electronic components that have built this circuit (in this case, resistor and LED diode, as shown below).

Simple example of series circuit

• Parallel circuits – when the current is „flowing” inside two or more circuit branches, and then it again sums into one current stream at the node. This phenomenon is described by the 1st Kirchhoff’s law. In the picture below, the capacitor C is connected in parallel with the resistor R and the LED diode D from the point of view of the power source U1.

Simple example of parallel circuit

Another very important parameter that describes electrical circuits is their linearity, which depends on the linearity of its electronic components. When there is even one nonlinear element in the electronic circuit (such as diode or transistor) – the whole circuit loses its linear character. Please note that Ohm’s law does not apply to nonlinear circuits.