1 / 31

Current and Potential Difference

Current and Potential Difference. Text 11.1: 432-443. Agenda. Inquiry – Pick an Electric Fish?!?! Current Electricity Electric Circuits Electrochemical cells Potential Difference Electron Transfer – Measuring Current Quick Lab – Using an Ammeter & Voltmeter Check & Reflect Questions.

tawny
Download Presentation

Current and Potential Difference

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. Current and Potential Difference Text 11.1: 432-443

  2. Agenda • Inquiry – Pick an Electric Fish?!?! • Current Electricity • Electric Circuits • Electrochemical cells • Potential Difference • Electron Transfer – Measuring Current • Quick Lab – Using an Ammeter & Voltmeter • Check & Reflect Questions

  3. Learning Goal • By the end of this class, we should be able to: • Define and identify the correct units and measurement tool of current • Compare and contrast AC and DC current • Identify the components of a simple current and their functions

  4. Inquiry – Pick an Electric Fish!?! Elephantnose Fish Pacific Electric Ray Electric Eel Answer the following questions: • How do these aquatic species generate electricity? • What do they use electricity for?

  5. Current Electricity • The electricity produced by these animals is similar to static charge • Unfortunately we cannot use static charge to run electronic devices because it does not flow • It is STATIC!! • To power electric devise you need a steady flow of electrons

  6. Electron Flow • Electrons will only continually move if 2 conditions are met: • There is an energy source • There is a complete track/path for them to flow through • The path is called a circuit • The continuous flow of electrons in a circuit is called current electricity

  7. Electric Circuits • A circuit always includes an energy source, a conductor and a load • An energy source provides the energy to the circuit • A conductor is the path through which the energy flows • An electrical load is a device that converts electrical energy to another form of energy

  8. Electric Circuits • Many circuits also include a switch • A switch is a device that turns a circuit on or off by closing or opening the circuit • Only when the switch is closed and the circuit is complete can electrons flow

  9. Electric Circuits – Label It!

  10. Electrochemical Cells – Converting • A simple electrochemical cell includes an electrolyte and two electrodes • An electrolyte is a liquid or paste that conducts electricity because it contains chemicals that form ions (EX: citric acid) • Electrodes are metal strips that react with the electrolyte. There are two electrodes in a battery, such as zinc and copper

  11. Electrochemical Cells – Batteries • A battery has chemical potential energy in the electrolyte in its electrochemical cells • Each electrochemical cell is a package of chemicals that converts chemical energy into electrical energy that is stored in charged particles

  12. Electrochemical Cells – Reaction • The reaction between the electrolyte and electrodes results in the electrons to collect on one electrodes (making it negative) and the other to be electron deficient (positive)

  13. Types of Electrochemical Cells • Wet Cell • Has a liquid electrolyte e.g. car battery • Dry Cell • Uses a paste of a liquid electrolyte • Fuel Cell • Chemical reaction with a fuel i.e. hydrogen

  14. Electrochemical Cells – Label It!

  15. Electrochemical Cells – Recycling • 50% of all heavy metals in landfills come from batteries • Contain toxic materials i.e. nickel, cadmium, and lead • What are some responsible options?

  16. Electrochemical Cells – Inquiry • Is it possible to charge an iPod from with a piece of fruit? http://www.youtube.com/watch?v=PuiPDBA3XZI

  17. Learning Checkpoint • Answer the following questions: • How is current electricity different from static electricity? • What is an electric circuit? • List three components of an electric circuit. • What is the difference between an electrolyte and an electrode • Why should dry cells be recycled rather than thrown in the trash?

  18. Potential Difference • Each electron has electric potential energy • Potential energy is energy stored in an object i.e. battery • EX: An apple on a tree • The higher the apple is the more potential energy it has • The potential energy can be converted into another form of energy- like kinetic energy (motion)

  19. Potential Difference – Voltage (V) • Battery = chemical potential energy in the electrolyte • Difference of electrons between (+) & (-) • Electrons are attracted to the positive terminal

  20. Potential Difference – Voltage (V) • Potential Difference or Voltage (V) • Electric potential between two points is called the potential difference or voltage. • Higher voltage = < potential energy of each electron • Must be measured across the load. Volts (V)

  21. Electrons = Energy Transfer • So when you turn on a light switch, you close the circuit in wiring in the wall which turns on the light! • BUT how does it happen SO fast?

  22. Electron Transfer – Hmmm… • Think of it as a faucet / hose • If there is already water in the hose - the water can come out of the end of the hose right away • The electrons do not travel from the switch to the bulb • But from the wire right near the bulb into it!

  23. Electron Transfer –Electron Flow • With electrons it is similar • When an energy source is connected to a circuit, electrons in the conductor start to repel and push other electrons nearby • They push each other forward like you do in the café line!

  24. Electron Transfer - Called Current! • Electric current is a measure of the amount of electric charge that passes by a point in an electrical circuit each second • Like water in a stream • Water keeps flowing unless the source dries up • i.e. electrons will continue to flow until the battery stops separating charge

  25. Electron Transfer – Current • If electrons flow in one direction it is called a direct current (DC) • Like in batteries (low-powered) • If electrons can move back and forth at regular intervals called cycles are called alternating current (AC) • i.e. big power lines

  26. Electron Transfer – Current

  27. Electron Transfer – Measuring Current • Current is measured with an ammeter • Unit is amperes (A) • Black is negative and red is positive when measuring an ammeter or voltmeter

  28. Electron Transfer – Current vs. Voltage • An Ammeter measures the flow of electrons at any point in the circuit. • A Voltmeter measures the potential difference across the load Where else could you measure Amperes? Where else could you measure voltage?

  29. Measuring Current • Quick Lab • Build a circuit with one battery, one switch, and one bulb. • Open your circuit and connect the ammeter as show in diagram A. • Close and test your circuit. Record the current in amperes (A) • Repeat steps 2 and 3. This time connect the ammeter as shown in diagram B.

  30. Measuring Voltage • Quick Lab • Build a circuit with one battery, one switch, and one bulb. • Connect the voltmeter to the circuit as shown in diagram A • Close the circuit and record measurement • Repeat steps 2 and 3. This time connect the voltmeter as shown in diagram B.

  31. Check & Reflect • Answer the following questions in your textbook: • Q. 1, 2, 3, 4, 5, 6, & 12 page 447

More Related