Ohm's Law

Section 1: Understanding Ohm’s Law

• Ohm’s Law is a fundamental principle that all electronic engineers should understand. This basic but essential law defines the relationship between current, voltage, and resistance in an electrical circuit.
• It can be mathematically expressed as I = V / R, where I is the current in amperes, V is the voltage in volts, and R is the resistance in ohms.
• The law gets its name from the German physicist Georg Simon Ohm, who first formulated it in 1827.

Section 2: Practical Implications of Ohm’s Law

• Understanding Ohm’s Law is key to designing and understanding how electrical circuits operate.
• It allows you to predict how much current will flow through a circuit for any given voltage and resistance.
• It’s essential for calculations involving power. To find the power (P) in a circuit, Ohm’s Law can be combined with the formula P = IV, where P is power in watts, I is current and V is voltage.

Section 3: Limitations and Conditions of Ohm’s Law

• Ohm’s law holds true for many materials under various conditions, but it’s not universal. There are materials referred to as non-ohmic, for which the current is not directly proportional to voltage.
• The law primarily holds for conductors and semi-conductors under constant temperature conditions. If temperature varies significantly, the resistance can also vary - altering the relationship between current and voltage.
• Ohm’s law doesn’t apply to circuits where electrical quantities vary with time, such as in AC circuits. For these circuits, more complex laws based on calculus are required.

Section 4: Relevance in Advanced Electronics

• While Ohm’s Law is a basic concept, it’s integral to understanding more complex properties like capacitive and inductive reactance, impedance in AC circuits, and total complex power.
• Mastery of these concepts provides the foundation for understanding more advanced topics in electronics, such as the function of filters, transformers, power supplies, and amplifiers.