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Electricity

This educational overview explores the fundamentals of electricity, focusing on the flow of charges in atoms, the elements of electric circuits, and the roles of conductors and insulators. Learn about voltage, resistance, and Ohm’s Law, and understand the differences between series and parallel circuits. Additionally, the text delves into the concepts of direct and alternating current, and how energy conversion takes place in batteries and generators. Discover how electricity relates to magnetism and its significance in everyday applications.

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Electricity

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  1. Electricity The flow of charges

  2. Atoms • Made up of: • Nucleus: Protons and neutrons • Electrons: negative charge orbit nucleus

  3. Current • Flow of electrons • Measured in Amperes (Amps) • Electrons passing per second

  4. Circuit • Must have complete, unbroken path for current to flow • 3 Parts: • Load: device run by electricity • Wires: path for electron flow • Source: moves the electrons through the wire • Battery, generator, wall socket (power plant)

  5. A break in the circuit stops electricity from flowing

  6. Conductors • Materials allowing electrons to flow • Examples: • metals: electrons loosely held, move easily • Copper is one of the best

  7. Insulators • Do not allow electricity to flow • Examples: rubber, plastic • Electrons held tightly, will not move easily

  8. Voltage • Measures the force “pushing” electrons • Volt (v) as unit • Higher voltage is higher potential to push electrons through circuit

  9. Water dam Lower Potential energy =Low voltage Higher Potential energy=high voltage

  10. Resistance • Force working against (“resisting”) the flow of electrons • Measured in Ohms (Ω) • All parts of circuit “slows the flow”

  11. V I = R Ohm’s Law • Tells how current, voltage, resistance are related • Current = voltage resistance

  12. Practice Ohm’s Law • A 9 volt battery is used to light 3 bulbs with a resistance of 0.5 Ω each. Wires and a switch add another 3 ohms of resistance. How much current (amps) is flowing through the circuit? • Plan • What information is given? • 9 volts, 3 bulbs x 0.5 ohms = 1.5 ohms plus 3 ohms for total of 4.5 ohms. • What formula do I use? • I = v / r • I = 9 v / 4.5 Ω • Solve • I = 2 amps • Check:Does it make sense? • The current is less than the voltage because the resistance is reducing the flow

  13. Circuits and Current Direction

  14. Series Circuit • Only one path for electricity to flow • What happens if one bulb goes out? • Will the bulbs be dimmer or brighter than a parallel? Load (bulb) Switch

  15. Parallel circuit • More than one path for electricity to flow • Each load on separate circuit • What happens if one bulb goes out? • Compare series/parallel to water supply

  16. Current Direction • Current always flows in one direction: From negative to positive AC vs. DC

  17. Direct CurrentDC • Charges always flow in same direction, from negative terminal to positive terminal • Battery (cells)

  18. anode collector plastic seal plastic sleeve anode steel jacket Case sleeve Cell straps cathode Negative terminal cathode collector electrolyte Positive terminal Cells and Batteries 9 Volt Battery • Convert chemical energy to electrical energy • Potato clock Electron acceptor Electron donor

  19. Other sources of DC • Thermocouple: convert heat to electricity • Solar cells: convert solar energy to electricity

  20. Alternating CurrentAC • Charges flow from negative to positive but switch directions back and forth (alternate) • House current

  21. Producing AC current • Induction: Coil of wire and magnet produce electricity • It’s electro-magnetism! • Generator: converts mechanical energy to electrical energy • Motor: converts electrical energy to mechanical energy

  22. Electromagnetism • Magnetism and Electricity are closely related • Electric current causes magnetic fields • Cell phones, television, light • Magnets can cause an electric current to flow • Generators

  23. Power • Measures how fast energy is transferred from one form to another • Measured in Watts • Power = voltage x current • P= V I • A 100 watt light bulb changes or uses electrical energy to light energy twice as fast as a 50 watt bulb • Brainpop on current

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