V = IR

Definition

V = IR, also known as Ohm's Law, is a fundamental relationship in electrical circuits that describes the relationship between voltage (V), current (I), and resistance (R). This equation is a critical concept in understanding the behavior of electrical components and circuits.

5 Must Know Facts For Your Next Test

1. Ohm's Law states that the current through a conductor is directly proportional to the voltage applied across it, and inversely proportional to the resistance of the conductor.
2. The V = IR equation can be rearranged to solve for any one of the three variables (voltage, current, or resistance) if the other two are known.
3. Resistors in series follow the rule that the total resistance is the sum of the individual resistances, while resistors in parallel follow the rule that the total resistance is the reciprocal of the sum of the reciprocals of the individual resistances.
4. The V = IR relationship is crucial in understanding the behavior of electrical circuits, as it allows for the calculation of power dissipation, voltage drops, and current flows.
5. Ohm's Law and the V = IR equation are fundamental to the study of electrical engineering and are widely used in the design and analysis of electronic devices and systems.

Review Questions

• Explain how the V = IR equation relates to resistors in series.
  • For resistors in series, the total voltage drop across the circuit is the sum of the individual voltage drops across each resistor. Using the V = IR equation, we can calculate the voltage drop across each resistor by multiplying the current (I) by the resistance (R) of that particular resistor. The total resistance of the series circuit is the sum of the individual resistances, so the total voltage drop can be calculated by multiplying the total current (I) by the total resistance (R).
• Describe how the V = IR equation is used to analyze resistors in parallel.
  • When resistors are connected in parallel, the voltage drop across each resistor is the same, as they are all connected to the same voltage source. Using the V = IR equation, we can calculate the current through each resistor by dividing the voltage (V) by the resistance (R) of that particular resistor. The total current in the parallel circuit is the sum of the individual currents through each resistor. The total resistance of the parallel circuit can then be calculated using the reciprocal of the sum of the reciprocals of the individual resistances.
• Evaluate the importance of the V = IR equation in the context of electrical circuits and power dissipation.
  • The V = IR equation is fundamental to understanding the behavior of electrical circuits and the flow of power within them. By applying this equation, you can determine the voltage drop across a resistor, the current flowing through a circuit, or the resistance of a component. This information is crucial for calculating power dissipation, which is the amount of energy lost as heat in a circuit. Power dissipation is calculated as P = IV = I^2R = V^2/R, where the V = IR equation is a key component. Understanding power dissipation is essential for the design and analysis of efficient and safe electrical systems, as excessive power dissipation can lead to overheating and potential failures.

Related terms

Voltage: Voltage, also known as potential difference, is the force that drives the flow of electric current in a circuit.

Current: Current is the rate of flow of electric charge, measured in amperes (A).

Resistance: Resistance is a measure of the opposition to the flow of electric current in a circuit, measured in ohms (Ω).