Resistor

Definition

A resistor is a passive electronic component that is used to control or limit the flow of electric current in a circuit. It is a fundamental building block of electronic circuits, playing a crucial role in various topics, including Ohm's law, series circuits, parallel circuits, and electric power.

5 Must Know Facts For Your Next Test

1. Resistors are classified by their resistance value, measured in ohms (Ω), which determines the amount of opposition to the flow of electric current.
2. The power rating of a resistor, measured in watts (W), indicates the maximum amount of power it can safely dissipate without being damaged.
3. Resistors can be used to control the voltage and current in a circuit, allowing for the regulation of power and the protection of sensitive electronic components.
4. In series circuits, resistors are connected one after another, and the total resistance is the sum of the individual resistor values.
5. In parallel circuits, resistors are connected to the same terminals, and the total resistance is calculated using the reciprocal of the sum of the reciprocals of the individual resistor values.

Review Questions

• Explain how the resistance value of a resistor affects the flow of electric current in a circuit, as described by Ohm's law.
  • According to Ohm's law, the relationship between voltage (V), current (I), and resistance (R) is given by the equation V = IR. This means that as the resistance value of a resistor increases, the current flowing through the circuit will decrease, assuming the voltage remains constant. Conversely, if the resistance value decreases, the current will increase, again assuming the voltage remains the same. Resistors are used to control and limit the flow of electric current in a circuit, allowing for the regulation of power and the protection of sensitive electronic components.
• Describe the role of resistors in series and parallel circuits, and how their configuration affects the total resistance of the circuit.
  • In a series circuit, resistors are connected one after another, forming a single path for the flow of electric current. The total resistance of a series circuit is the sum of the individual resistor values. This means that increasing the number of resistors in a series circuit will increase the total resistance, which will in turn decrease the current flowing through the circuit. In a parallel circuit, resistors are connected to the same set of terminals, allowing multiple paths for the flow of electric current. The total resistance of a parallel circuit is calculated using the reciprocal of the sum of the reciprocals of the individual resistor values. This means that increasing the number of resistors in a parallel circuit will decrease the total resistance, which will in turn increase the current flowing through the circuit.
• Analyze how the power rating of a resistor is related to its ability to safely dissipate power in an electric circuit, and explain the importance of selecting the appropriate power rating for a given application.
  • The power rating of a resistor, measured in watts (W), indicates the maximum amount of power it can safely dissipate without being damaged. If the power dissipated in a resistor exceeds its power rating, the resistor may overheat, leading to potential failure or even fire hazards. The power dissipated in a resistor is given by the equation P = I^2R, where P is the power, I is the current, and R is the resistance. When designing an electronic circuit, it is crucial to select resistors with a power rating that is sufficient to handle the expected power dissipation, taking into account factors such as the maximum current, voltage, and the specific application requirements. Choosing the appropriate power rating for a resistor ensures the safe and reliable operation of the circuit.

Related terms

Ohm's Law: Ohm's law is a fundamental relationship that describes the relationship between voltage, current, and resistance in an electrical circuit.

Series Circuit: A series circuit is a configuration where components are connected end-to-end, forming a single path for the flow of electric current.

Parallel Circuit: A parallel circuit is a configuration where components are connected to the same set of terminals, allowing multiple paths for the flow of electric current.