Notes on Basic Electrical Circuits

Introduction to Electrical Circuits

  • Presenter: Boing King
  • Location: Air Conditioning Department, Electrical Controls Lab
  • Focus: Overview of basic concepts of electricity and introduction to simple electrical circuits.

Review of Basic Electrical Concepts

  • Three Aspects of Electricity:
    • Voltage (E): The difference in electric potential energy between two points in an electric field.
    • Amperage (I): The measure of electric current, which represents the flow of electrons in a circuit.
    • Resistance (R): The opposition to the flow of electric current, resulting in the conversion of electrical energy to thermal energy.
    • Acronym: Voltage (E), Amperage (I), Resistance (R) can be remembered as EIR.

Types of Circuits

  • The focus centers on three major types of circuits: Simple Circuit, Series Circuit, and Parallel Circuit.

Simple Circuit

  • Definition: A circuit that consists of only one load.
  • Components:
    • Source: Provides the electrical energy (e.g., plug in the wall).
    • Path: The conductive path through which electricity flows (e.g., wires).
    • Load: The device that consumes electrical energy (e.g., light bulb).
  • Flow of Electrons:
    • Electrons flow in the hot wire from the source through the load (light bulb), completing the circuit and heating the bulb due to resistance.
    • Described using a metaphor of BB movement (representing electron flow).
  • Characteristics:
    • Only a single load; the light bulb lights up due to resistance.

Series Circuit

  • Definition: A circuit with two or more loads connected in a sequence or series.
  • Components:
    • Source: Same as in the simple circuit.
    • Path: The route electrons take is through each series-connected load.
    • Loads: Multiple loads sharing the same path.
  • Characteristics:
    • Total resistance increases with additional loads (similar to kinking a water hose).
    • Voltage is divided among the loads:
    • If the total supply voltage is 120 volts:
      • Each bulb receives 60 volts if they have equal resistance.
  • Implication: Increased resistance can lead to dimmer bulbs since voltage is divided.

Parallel Circuit

  • Definition: A circuit where two or more loads are connected along multiple paths.
  • Components:
    • Source: Provides electrical energy.
    • Path: Conductive paths leading to different loads.
    • Loads: Multiple loads receiving electricity simultaneously.
  • Characteristics:
    • Each load receives the same voltage from the source (e.g., all loads see 120 volts in a standard circuit).
    • Load sharing is significant; each load draws its required amperage, increasing total current (or BB movement) in the main wire.
    • As more loads are connected in parallel, total current increases:
    • Total current is the sum of currents through each load.
  • Common Use: Most popular type of circuit in household wiring due to equal voltage across loads.

Electrical Control Components

  • Switches:
    • Type: Single Pole, Single Throw (SPST) switches.
    • Functionality: Controls the path, allowing or stopping the current flow through each load.

Conclusion

  • Summary: The three types of circuits discussed are:
    • Simple Circuit: One load, straightforward flow.
    • Series Circuit: Multiple loads, voltage divided, increased resistance.
    • Parallel Circuit: Multiple paths, same voltage for all loads, total current increases.
  • Contact Information: For further questions, students are encouraged to email the presenter.