Conductors, Insulators, and Electronic Devices

Conductors

• Definition: Conductors are materials that allow a relatively free flow of electric current.

• Characteristics:

  • Abundance of free electrons enables electric conductivity.

• Common Examples:

  • Copper: Widely used due to high electron availability.

  • Aluminum and Gold: Also good conductors of electricity.

  • Water: Conducts electricity due to mineral impurities.

• Non-conductors: Most nonmetallic elements do not conduct well since their electrons are bound and do not move freely.

Insulators

• Definition: Insulators have virtually no free electrons, making them poor conductors of electricity.

• Benefits of Insulators:

  • Used to contain and control electricity flow.

• Materials:

  • Rubber, Plastic, Glass, and Ceramic: Common insulating materials.

  • Used to cover wires/components and support power lines (e.g., glass on power poles).

Electronic Devices

• Definition: A device can refer to an individual piece of equipment or component within an electrical circuit.

• Importance of Circuits:

  • An electric circuit is a closed pathway for electric current to flow.

  • Must be closed for current to function, otherwise called an open circuit.

Grounding

• Definition: Grounding connects a device electrically to the earth via a conductor, neutralizing charge.

• Functionality:

  • Positively charged objects take on electrons; negatively charged objects give up electrons to achieve neutrality.

• Grounding in Devices:

  • Three-prong plugs include a ground wire that prevents electrical shock by redirecting excess current into the ground.

Circuit Elements and Functions

• Common Circuit Elements:

  • Resistor: Inhibits electron flow.

  • Battery: Provides electrical potential.

  • Capacitor (Condenser): Temporarily stores electric charge.

  • Ammeter: Measures electric current.

  • Voltmeter: Measures electric potential.

  • Switch: Turns the circuit on or off by offering infinite resistance.

  • Transformer: Increases/decreases voltage (AC only).

  • Rheostat: Variable resistor controlling current flow.

  • Diode: Allows electrons to flow in one direction only.

Protective Devices

• Purpose: Protect circuits and individuals from malfunction (e.g., short circuits).

• Fuses:

  • Wire that melts if current exceeds safe level, opening the circuit.

• Circuit Breakers:

  • Automatically open the circuit when current is too high, protecting the system.

Basic Circuit Schematics

• Key Elements:

  • Typical representation includes a battery, resistor, and switch.

  • Open switch indicates no current flow.

Measuring Devices

• Voltmeter: Measures voltage across components in a circuit.

• Ammeter: Positioned to measure current flow through segments of a circuit.

• Ohmmeter: Measures resistance across a resistor, allowing for total resistance assessment by summing individual resistances in a series circuit.

Review Questions

1. A closed circuit will conduct electricity — True: The switch must be closed for current flow.

2. Insulators are characterized by Few Free Electrons: They do not conduct electricity well.

3. Grounded Electrical Device Behavior: Gives up electrons until neutral if there’s an abundance of electrons.

4. Common conductor is Copper, not insulating materials like glass or plastic.

5. Resistor symbol corresponds to letter B in circuits.

6. Function terms:

   • Inhibits flow of electrons: Resistor

   • Momentarily stores electric charge: Capacitor

   • Measures electric current: Ammeter

   • Allows electrons to flow in one direction: Diode

   • Increases/decreases voltage: Transformer