Fundamentals of Electricity and Basic Electronics Concepts
Electricity Fundamentals
Matter is formed by atoms consisting of negatively charged particles (electrons) and positively charged particles (protons). Between these particles, there are forces of attraction or repulsion that generate a type of energy called electricity.
Material Classification by Electrical Behavior
According to the way materials behave when subjected to an electrical force, we classify them into:
- Conducting materials: These transmit electrical energy across their surface. We call this transfer of charges electrical current, and it is produced in conducting materials.
- Insulating materials: These block the movement of electrons across them.
- Semiconductor materials: These can behave as conductors or insulators depending on the conditions.
Introduction to Electronics
Electronics is the branch of physics that studies the control of the movement of electrons in semiconducting materials. The behavior of semiconducting materials is halfway between conducting and insulating materials.
Analog vs. Digital Electronics
Analog electronics studies systems where the variables (current, voltage, etc.) can take on any values over time, i.e., they are continuous. A small change in any of these variables can create a big change in the behavior of the circuit.
Digital electronics studies systems where the information is encoded in discrete values (traditionally zeros and ones), and a voltage range is assigned to each. Although every system has its own logic levels, these are usually between 0 and 18 volts, depending on the type of components used.
Types of Electrical Current
Direct current (DC) is the current produced when electrons always move in the same direction inside an electric circuit. These electrons move from the negative terminal of the cell in the circuit to its positive terminal.
Alternating current (AC) is the electrical current whose value and direction vary cyclically in a circuit. This type of current is generated in power plants and is the one we find in household plug sockets. Most electrical and household appliances are powered by alternating current.
Fundamental Electrical Quantities
Current (I)
Current is the variable that tells us how many electrons flow through the cross-section of a conductor per unit of time. Its unit of measurement in the International System is the ampere (A).
Voltage (V)
Voltage is the variable that tells us the difference in electrical energy per unit of charge between two points in a circuit. Its unit of measurement in the International System is the volt (V).
Resistance (R) and Ohm’s Law
Resistance is the variable that tells us the opposition to the passage of an electric current. Its unit of measurement in the International System is the ohm (Ω). Ohm’s Law states that the current in a circuit is directly proportional to the electric potential difference (voltage) impressed across its ends and inversely proportional to the total resistance offered by the external circuit.
Equivalent Circuits
To perform the electrical calculations of a circuit with several resistors, we calculate the value of a single resistor, equivalent to the association of the resistors in the circuit. The circuit formed with the equivalent resistor is called an equivalent circuit. We can obtain three things from this circuit:
- The currents flowing through the circuit
- The potential drops across the components
- The dissipated power and the delivered power