Understanding Resistance, Reactance, and Impedance

Introduction

• Definitions of resistance, reactance, and impedance.
• Importance of understanding these concepts in electrical circuits.

Current Flow in Circuits

• Direct Current (DC): Current flows in one direction with constant voltage.
• Alternating Current (AC): Voltage varies, causing current to change direction and magnitude frequently.
  • Voltage and current graphs for DC show constant values.
  • AC voltage graph follows a sine wave pattern.

Impact of Circuit Components

• Components in AC and DC circuits influence electron flow:
  • Each component impedes the movement of electrons, reducing current flow.
  • Behavior differs between AC and DC circuits:
    • In AC, current changes can lag or lead voltage due to component characteristics.

Types of Current Changes

1. Resistance: Current decreases simultaneously with voltage in DC and AC circuits.
2. Reactance:
   • Current change occurs after a voltage change (lag) - Inductive Reactance.
   • Current change occurs before a voltage change (lead) - Capacitive Reactance.

Understanding Resistance and Reactance

• Water Analogy:
  • Water flow parallels current flow in circuits.
  • Resistors: Similar to a narrow nozzle; they impede flow (current).
  • Inductors: Act like a water wheel; they resist changes in flow (current).
  • Capacitors: Act like an elastic chamber; they influence flow leading voltage changes.

Resistors

• Oppose current flow in both AC and DC circuits.

Inductors

• Delay current changes; significant in AC circuits where current lags behind voltage.

Capacitors

• Allow current to lead voltage changes, only observable in AC circuits.

Impedance

• Definition: Cumulative effect of resistance, inductive reactance, and capacitive reactance.
• Impedance signifies how a component modifies current in a circuit.

Conclusion

• Key factors influencing current:
  • Resistance decreases current (DC and AC).
  • Inductive reactance causes current lag (AC only).
  • Capacitive reactance causes current lead (AC only).
• Understanding these concepts is crucial for analyzing electrical circuits.