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). It states that the voltage across a resistor is directly proportional to the current flowing through it, and the constant of proportionality is the resistance of the resistor.

5 Must Know Facts For Your Next Test

1. Ohm's Law is a fundamental principle in the study of electrical circuits and is used to analyze and design various electronic devices and systems.
2. The V = IR equation can be rearranged to solve for any one of the three variables (V, I, or R) if the other two are known.
3. Ohm's Law applies to both direct current (DC) and alternating current (AC) circuits, but the interpretation of the variables may differ.
4. The resistance in a circuit can be affected by factors such as temperature, material composition, and the geometry of the conductor.
5. Ohm's Law is a linear relationship, meaning that if one variable changes, the other two will change proportionally.

Review Questions

• Explain how the V = IR equation can be used to calculate the current in a circuit if the voltage and resistance are known.
  • To calculate the current in a circuit using the V = IR equation, you would rearrange the equation to solve for I, which gives you I = V/R. By inputting the known values for voltage (V) and resistance (R), you can then calculate the current (I) flowing through the circuit. This is a useful application of Ohm's Law that allows you to determine the amount of current in a circuit based on the voltage and resistance present.
• Describe how the resistance in a circuit can affect the relationship between voltage and current as described by Ohm's Law.
  • According to Ohm's Law, the relationship between voltage (V), current (I), and resistance (R) is V = IR. This means that as the resistance in a circuit increases, the current will decrease for a given voltage, and vice versa. The resistance acts as an obstacle to the flow of current, and higher resistance will result in less current flowing through the circuit for the same applied voltage. Conversely, lower resistance will allow more current to flow for the same voltage. Understanding this relationship is crucial for analyzing and designing electrical circuits.
• Evaluate how Ohm's Law can be used to predict the behavior of electrical circuits under different conditions, such as changes in voltage or resistance.
  • Ohm's Law, expressed as the equation V = IR, provides a powerful tool for predicting the behavior of electrical circuits under various conditions. By rearranging the equation, you can solve for any of the three variables (V, I, or R) if the other two are known. This allows you to anticipate how changes in one variable will affect the others. For example, if the voltage in a circuit is increased while the resistance remains constant, you can use Ohm's Law to determine that the current will also increase proportionally. Similarly, if the resistance is increased while the voltage remains constant, you can predict that the current will decrease. This predictive capability of Ohm's Law is essential for designing, analyzing, and troubleshooting electrical circuits across a wide range of applications.

Related terms

Voltage:

Voltage, or electromotive force (EMF), is the potential difference between two points in an electrical circuit, measured in volts (V).

Current:

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

Resistance:

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