electric circuits

Electricity Overview

  • Electricity Types

    • Static Electricity: Electric charges that do not move.

    • Current Electricity: Electric charges that flow from one place to another.

Electric Current

  • Definition: Movement or flow of electric charges.

  • Purpose: Converts electrical energy into other forms of energy as needed using electric circuits.

Electric Circuits

  • Requirement: Current electricity needs a circuit to flow.

  • Definition of Circuit: A path for electricity to travel.

  • Main Components of Circuits:

    1. Source of Electricity

      • Essential for a circuit to function.

      • Examples: Cell, battery, portable generator, wall outlet.

      • Symbol:

        • Cell

        • Battery + (+) - (_)

    2. Electrical Load

      • Converts electrical energy into usable forms (light, motion, etc.).

      • Examples: Motors, lights, resistors.

      • Symbol:

        • Light

        • Motor

        • Resistor (R)

    3. Electrical Circuit Control Device

      • Used for controlling the device; can be manual or automatic.

      • May be internal (e.g., thermostat).

      • Symbol:

        • Switch (open)

        • Switch (closed)

    4. Connectors

      • Wires that provide a path for electric current.

      • Must be conductors.

      • Symbols:

        • Wire

        • Grounded wire

Circuit Functions

  • More wires may be added for functionality.

  • Open vs. Closed Circuits:

    • Closed Circuit: Operating condition; current flows (Switch is "on").

    • Open Circuit: Non-operating condition; current does not flow (Switch is "off").

    • Note: Electrons flow from the negative terminal to the positive terminal.

Circuit Symbols

  • Common symbols used in circuit diagrams:

    • Wire (0): Conductor allowing electron flow.

    • Cell/Battery: Electrical source, longer side is positive terminal, shorter side is negative terminal.

    • Lamp/Light Bulb: Converts electricity to light and heat.

    • Resistor: General load converting electricity to heat.

    • Switch: Opens and closes the circuit.

    • Ammeter (A): Measures current, connected in series.

    • Voltmeter (V): Measures voltage, connected in parallel.

Schematic Circuit Diagrams

  • Drawing circuits using right angles and standard symbols promotes clarity.

Cells and Batteries

  • Cells: Source of electrical energy; often confused with batteries.

  • Types of Cells:

    • Wet Cells:

      • Consist of two metal pieces in a liquid, usually an acid.

      • Example metals: Zinc and copper.

    • Dry Cells:

      • Use a moist paste instead of a liquid, making them more convenient to carry.

Cell Types

  • Primary Cells:

    • Non-rechargeable; irreversible chemical reactions.

    • Must be discarded when depleted.

  • Secondary Cells:

    • Rechargeable; reversible chemical reactions.

    • Can convert collected energy back into electricity.

Fuel Cells

  • Utilize fuels (e.g., hydrogen) to generate electric current.