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Circuits__continued_

Circuits Overview

  • Current vs Static Electricity

  • Open and Closed Circuits: Understanding the flow of current and the role of each component

  • Sources, Loads, Connectors, Switches: Essential components for circuit functionality

  • Types of Cells: Different kinds of cells affecting circuit design

What Makes the Current Flow?

Potential Energy

  • Higher objects have greater potential energy.

    • Example: An apple in a tree; the higher it is, the greater the potential energy.

  • Balloons: The air inside has potential energy due to high pressure, leading to air escaping when released.

Power Sources

  • Batteries & Cells: Utilize chemical potential energy in electrolytes to energize electrons.

    • One terminal: excess electrons (high pressure)

    • Other terminal: deficit of electrons.

Electric Potential Difference

  • Definition: Potential energy per coulomb of charge, measured in Volts (V).

  • Voltage: Another term for electric potential difference.

  • Potential difference indicates differences in electric potentials at two points, such as battery terminals.

Measuring Potential Difference

  • Tools Used: Voltmeter

  • Usage: Leads are placed on either side of a circuit component to measure potential difference.

Current Overview

Analogy

  • Electrons in a wire resemble marbles in a tube; pushing one marble transmits energy to all.

Electric Current

  • Definition: Flow of electric charge through a conductor, measured in coulombs per second.

  • Requirements for Flow: Presence of a source producing potential difference and a closed circuit.

Measurement of Current

  • Unit: Ampere (1 C/s)

  • Measurement Tool: Ammeter, which is inserted into a circuit to determine current.

Types of Current

Direct Current (DC)

  • Flows in one direction.

  • Examples: Batteries, computer power supplies.

Alternating Current (AC)

  • Direction changes multiple times per second (60x/s in North America, 50x/s in Europe).

  • Household electricity is typically AC.

Electron Flow vs Conventional Current

  • Electron Flow: Movement from negative to positive.

  • Conventional Current: Describes flow from positive to negative due to historical convention.

  • Importance in engineering and circuit design.

Potential and Current in Circuits

  • Measuring potential across components, alongside current flow using various tools.

Electrical Resistance

  • Definition: Opposition to the flow of electric current.

  • Comparison with Straws: Thinner wires have more resistance similar to thinner straws.

  • Material Impact: Different materials have different resistances (e.g., Iron vs Copper).

Implications of Resistance

  • Energy Loss: Resistance leads to energy losses, typically as heat.

  • Measurement: Resistance is gauged in Ohms, using an ohmmeter.

Resistance in Circuits

  • More resistance means less current flow.

  • Example: Incandescent light bulb filaments act as resistors, generating heat and light.

Resistance and Pressure Analogy

  • Blowing through thin straw creates a pressure difference similar to a voltage drop across a resistor.

Factors Affecting Resistance in Wires

  1. Material

  2. Diameter (cross-sectional area)

  3. Length

  4. Temperature

Resistors in Circuits

  • Purpose: Regulate current and voltage in electronic circuits.

  • Values indicated via a color code for proper circuit design.