Background Theory > From Concept to Creation: Mastering PCB Design > Electronics Basics > Ohm’s law, Kirchhoff’s laws, passive & active components

Diving into the world of electronics requires a firm grasp of key principles and components. Among these, Ohm’s Law and Kirchhoff’s Laws are fundamental concepts that govern the behavior of electric circuits. Understanding these, along with the roles of passive and active components, is essential for anyone working in electronics. Let’s explore these concepts in detail:

Ohm’s Law

This is a fundamental principle in electronics that relates current, voltage, and resistance in a simple linear relationship. It's expressed with the formula:

V = I * R

where:

•V is the voltage across the component (in volts),

•I is the current flowing through the component (in amperes),

•R is the resistance of the component (in ohms).

Ohm's Law is foundational for analyzing circuits and understanding how these three quantities interact. It helps in predicting how a circuit behaves under different electrical conditions.

Kirchhoff’s Laws

These laws are critical for circuit analysis, particularly in more complex systems.

Kirchhoff's Current Law (KCL)

This law states that the sum of currents flowing into a junction (or node) is equal to the sum of currents flowing out of it. In essence, it's a reflection of the conservation of electric charge.

Kirchhoff's Voltage Law (KVL)

This law states that the sum of all the voltages around any closed loop in a circuit must equal zero. This is due to the conservation of energy, where the total energy gained in a loop from voltage sources is equal to the total energy lost through voltage drops (resistances, LEDs, etc.).

Both of these laws are routinely used to solve circuits, determine unknown values, and analyze complex networks of conductive pathways.

Passive Components

These are electronic components that don't require a source of energy to perform their intended function. They can only receive and store energy, or dissipate or release it. They don't amplify signals or produce energy. Common examples include:

Resistors

They oppose the flow of current, used for controlling voltage and current levels.

Capacitors

They store electrical energy in an electric field, used for filtering, timing, and power stabilization.

Inductors

They store energy in a magnetic field, typically to oppose changes in current or filter out certain frequencies.

Active Components

Unlike passive components, active components are capable of injecting power into a circuit and/or controlling electron flow. They usually require a source of energy to perform their operations and are used in amplifying, switching, or generating signals. Examples include:

Transistors

These can act as amplifiers or switches, controlling large amounts of current and voltage, and are foundational in modern electronic devices.

Integrated Circuits (ICs): These microchips can perform various functions, from simple logic operations to being the central processing units in computers. They consist of many transistors and other components.

Diodes: While sometimes considered passive, diodes are typically classed as active because they allow current to flow in one direction, used in converting AC to DC, among other tasks.

Conclusion

Together, these principles and components form the bedrock of electronic theory and practical circuit design. They provide the tools necessary for designing, analyzing, constructing, and troubleshooting circuits across all complexities and applications, serving as the fundamental language spoken by professionals in the field of electronics.