Ohm's law is the one of the fundamental principles in the electrical engineering, used to understand and analyze the electrical circuits. The Ohm's law describes the relationship between the voltage, current, and resistance providing engineers and enthusiast alike with powerful tool for circuit analysis and design. The Ohm's law is the law in which the electric current I in an electric conductor, at constant temperature, is determined as the ratio of the electric voltage U that causes the electric current to the electric resistance R. The key terms in ohm's law are voltage, current, and resistance.
Current
The current is symbolized with \(I\) and refers to the flow of the electric charge through a conductor or circuit component. The current is measured in amperes (amps) and indicates the rate at which charge moves past a give point in the circuit.
Resistance
Resistance is represneted with symbol R and quanti
Before delving into Ohm's Law itself, it's crucial to grasp the key terms involved:
- Voltage (V): Voltage, often denoted by the symbol "V," represents the electrical potential difference between two points in a circuit. It's measured in volts and signifies the force that drives electric charge to flow from one point to another.
- Current (I): Current, symbolized by "I," refers to the flow of electric charge through a conductor or circuit component. It's measured in amperes (amps) and indicates the rate at which charge moves past a given point in the circuit.
- Resistance (R): Resistance, represented by the symbol "R," quantifies the opposition to the flow of electric current in a circuit. It's measured in ohms and depends on factors such as the material, length, and cross-sectional area of the conductor.
Ohm's Law Equations
Ohm's Law is succinctly expressed through a set of mathematical relationships:
- Voltage-Current Relationship: The voltage across a conductor is directly proportional to the current flowing through it, given a constant resistance. Mathematically, this can be represented as: \begin{equation} U = R\cdot I, \end{equation} where the \(U\) is the voltage across the conductor, the \(I\) is the current flowing through the conductor, and \(R\) is the resistance of the conductor.
- Current-Voltage Relationship: The current flowing through a conductor is directly proportional to the voltage across it, given a constant resistance. This relationship is characterized by the equation: \begin{equation} I = \frac{U}{R}, \end{equation} where \(I\) is the current flowing through the conductor, \(U\) is the voltage across the conductor, and \(R\) is the resistance of the conductor.
- Resistance-Voltage Relationship: The resistance of a conductor is inversely proportional to the voltage across it, given a constant current. This can be expressed as: \begin{equation} R = \frac{U}{I}, \end{equation} where \(U\) is the voltage across the conductor, the \(I\) is the current flowing through the conductor, and \(R\) is the resistance of the conductor.
Examples
- Example 1 - Calculating Current - Resistor with a resistance of \(R = 10 [\Omega]\)] is connected to a voltage source of \(V = 20 [V]\). Calculate the current flowing through the resistors. \begin{eqnarray} I &=& \frac{U}{R}\\ I &=& \frac{20}{10} = 2 [A] \end{eqnarray} The current \(I\) flowing through the resistor is 2 [A].
- Example 2 - Calculating Resistance - The circcuit where a current of \(I = 5 [A]\) flows through a resistor where a voltage of \(V = 15 [V] \) is applied across it. Calculate the resistance of the resistor. Using Ohm's law we can calculate the resistance of the resitor \begin{equation} R = \frac{U}{I}\\ \end{equation} \begin{eqnarray} R &=& \frac{15}{5} \\ R &=& 3 [\Omega]. \end{eqnarray} The resistance of the resitor is equal to 3 [\(Omega\)].