1 / 13

Electricity

Electricity. Current, Resistors & Circuits. Current Electricity. The continuous flow of electrons through a circuit 2 conditions need to be met: Flow of electrons requires an energy source Electrons will not flow unless they have a complete path to flow through (circuit). Current.

garan
Download Presentation

Electricity

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Electricity Current, Resistors & Circuits

  2. Current Electricity • The continuous flow of electrons through a circuit • 2 conditions need to be met: • Flow of electrons requires an energy source • Electrons will not flow unless they have a complete path to flow through (circuit)

  3. Current • Measure of the amount of charge that passes through a given point (in a circuit) per second: • Measured in amperes (A) using an Ammeter • 2 types of current: • Direct Current (DC) • Alternating Current (AC) DC: electrons flow through a current in 1direction AC: electrons flow back and forth in cycles

  4. Conventional Current Hundreds of years ago, before the discovery of the electron, scientists inferred that when electric current flowed from one object to another, it did so because one object had “a greater amount of electricity” It was reasoned that electricity flowed from a higher, more positive source, to a lesser, more negative source

  5. Current vs Static Current electricity is the flow of electrons in a circuit through a conductor Static electricity is the electric charge that builds up on a surface and is discharged when given a path (does not continue to flow)

  6. Resistance • Resistance is the degree to which a substance opposes the flow of current through it • Resistance is measured in ohms (Ω) using an ohmmeter (part of a multimeter) • When a susbstance resists the flow of electrons, it slows down and converts the electrical energy into other forms of energy • The higher the resistance, the more energy gained from the electrons flowing through the circuit • Energy gained is radiated to surroundings as heat and/or light

  7. Resistance in a Circuit • The more resistance in a circuit, the smaller its conductivity • Example: Light Bulb Filament, Figure 11.18 (Pg 441)

  8. Resistance in a Wire • The longer and thinner the wire, the higher the resistance to electron flow • Example: Flow in Water Pipes, Figure 11.21 (Pg 443) • Factors affecting resistance of a wire Table 11.1 (Pg 443)

  9. Resistors and Potential Difference • Resistors can be used to control current or potential difference in a circuit • In a circuit, electrons have a higher potential difference before they enter a resistor compared to when they leave the resistor • Example: Potential Flow, Figure 11.19 (Pg 442) • Types of resistors: • Wire-wound: wire made of heat resistant metal wrapped around an insulator • Carbon composition: made of mainly carbon with other materials. Cheaper, less precise than wire-wound

  10. Circuit Diagrams • Schematic illustration of an electrical plan • Example: Circuit Symbols, Table 11.2 (Pg450) • 2 Types of circuits: • Series • Parallel

  11. Circuit Diagrams • Series • Components are arranged one after another • One path for electron flow – if pathway is interrupted, whole circuit will cease to function • Amount of current is same throughout • Current decreases when more resistors are added • Electrons use up all potential difference regardless of how many loads present

  12. Circuit Diagrams • Parallel • Components are arranged so that electrons can flow through more than 1 different path • Multiple paths for electron flow – if pathway is interrupted, other pathways are not interrupted • Current divides into each path. Pathway with least resistance will have greater current • Adding resistors in parallel decreases overall resistance (ie 1 strawvs 2) • Each load uses all the potential difference supplied by the battery

  13. Practice • Pg 457 #3-8

More Related