Electricity and Electric Circuits Notes

9.1 Flow of Electricity

What is Electricity?

  • Definition: Electricity is a form of energy that can be easily changed to other forms.

Sources of Electricity

  • Mainly two sources:
    1. Power Stations
      • Supply a lot of electricity.
      • Used in many electrical appliances.
    2. Electric Cells (Batteries)
      • Supply a little electricity.
      • Portable.
      • Safe.

How an Electrical Appliance Works

  • To make an electrical appliance work, electricity must flow through it.
  • The flow of electricity is called an electric current.
  • The path along which the electric current moves is called the electric circuit.

Electric Current

  • Definition: An electric current is the rate of flow of electric charges in a circuit.
  • An electric circuit consists of:
    • Electric cell
    • Connecting wire
    • Filament
    • Electron flow

Electric Charges

  • Electric charges are made up of positive charges (protons) and negative charges (electrons).
  • When these charges flow in a circuit, a current is produced.

Flow of Electricity Through a Circuit

  • In an electric circuit, the current flows from the positive terminal to the negative terminal of the battery.
  • The electrons move inside an electric cell because of the chemical reactions taking place inside it.
  • The flow of electrons is opposite to the flow of current.
  • Electricity is a flow of electrons around a circuit.
  • Simple circuit consists of:
    • Battery
    • Wire
    • Switch
    • Light bulb

Circuit Components and Symbols

  • Wire
  • Resistor
  • Voltmeter: Measures the voltage produced by a power supply.
  • Ammeter: Measures the flow of electrons in a circuit, which is known as current.
  • Cell
  • Battery
  • Switch

Instrument to Measure Current

  • An ammeter is an instrument used for measuring electric current.

AC, DC, and Conventional Current

  • In direct current (DC), the electric charge (current) only flows in one direction.
  • In alternating current (AC), the electric charge changes direction periodically.
  • Conventional current is the flow of positive charges and is directed from the positive terminal of the battery to the negative terminal.
  • Flow of electrons is opposite to the flow of conventional current (I)(I).