# Basic laws and concepts in electronics – Part 1

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 issues inherent in it, such as current, voltage, power, resistance and Ohm’s law or Kirchhoff’s laws. I will try as good as I can to explain “from the beginning” in my opinion the most important topics such as:

1. Electronic components.

2. Electrical circuits.

In the second part of this article, we will deal with 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 – this group contains components that can generate energy in the circuit or change their parameters, but also require external power supplies (e.g. diodes, transistors, tunnel diodes, integrated circuits).

Active electronic components

Passive electronic components

2. Electrical circuit – a collection of electronic components connected together by wires or conducting paths and forming a closed path for electrical current. The current in the circuit always chooses the path of the least resistance, always from the “positive” to the “negative”. Circuits can be suited either for Direct Current (DC) or Alternating Current (AC), which is determined by the time dependency of the current from the time I(t). We also distinguish two ways of connecting electronic components in a circuit and these are so-called:

• Series circuits – the end of one element connects to the beginning of the next one (in-line with the power source). The current in the circuit is the same, and the voltage across the circuit equals the sum of the voltage drops across the circuit components.

Simple example of series circuit

• Parallel circuits – when the current is „flowing” inside two or more circuit branches, and then it is again “merged” into one current stream. This phenomenon is described in th1 1st Kirchhoff’s law. In the example below, the capacitor C is connected in parallel with the resistor R and the diode D from the point of view of the power source U1.

Simple example of parallel circuit

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