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.