Fixed resistor

Definition

A fixed resistor is an electrical component that resists the flow of electric current and provides a constant resistance value. Unlike variable resistors, which can be adjusted to change their resistance, fixed resistors maintain their resistance regardless of the voltage or current passing through them. This consistent behavior makes them crucial in various electronic circuits for controlling current and voltage levels.

5 Must Know Facts For Your Next Test

1. Fixed resistors come in various types, including carbon film, metal film, and wire-wound, each with unique characteristics suited for different applications.
2. The resistance value of a fixed resistor is measured in ohms (Ω) and is typically indicated using a color code on the resistor's body.
3. Fixed resistors help protect sensitive electronic components from excessive current by limiting the amount that can pass through a circuit.
4. They are commonly used in voltage divider circuits, where they help set specific voltage levels for other components.
5. The power rating of fixed resistors, typically given in watts (W), indicates the maximum power they can safely dissipate without overheating.

Review Questions

• How does a fixed resistor differ from a variable resistor, and what implications does this have for circuit design?
  • A fixed resistor has a constant resistance value that does not change with voltage or current, while a variable resistor can be adjusted to alter its resistance. This difference impacts circuit design as fixed resistors provide predictable behavior essential for setting specific current or voltage levels, while variable resistors offer flexibility for tuning circuits. Designers choose between these components based on whether stable or adjustable resistance is needed for the application.
• Discuss how fixed resistors function within series and parallel circuits and how they affect overall circuit behavior.
  • In series circuits, fixed resistors add their resistances together, increasing the total resistance and affecting the current flowing through the circuit according to Ohm's Law. Conversely, in parallel circuits, fixed resistors provide multiple pathways for current, resulting in a lower total resistance than any individual resistor. This behavior means that fixed resistors play a critical role in determining how voltage is distributed across components and how much current flows through different branches of the circuit.
• Evaluate the importance of selecting appropriate power ratings for fixed resistors in electronic circuits and the potential consequences of improper selection.
  • Choosing the correct power rating for fixed resistors is crucial because it ensures that they can handle the heat generated by the current passing through them without failing. If a resistor is underrated and exceeds its power limit, it can overheat and potentially burn out, leading to circuit failure or damage to other components. Thus, understanding power ratings helps engineers design reliable circuits that function safely and efficiently under expected load conditions.

Related terms

Ohm's Law:

A fundamental principle in electronics that relates voltage (V), current (I), and resistance (R) in a circuit, expressed as V = IR.

Series Circuit: A type of electrical circuit in which components are connected end-to-end, resulting in the same current flowing through each component but different voltage drops across them.

Parallel Circuit: An electrical circuit configuration where components are connected across common points or junctions, allowing multiple paths for current to flow, which can affect the overall resistance.