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Electricity and Magnetism Circuits Electromagnets

Electricity and Magnetism Circuits Electromagnets. Chapter 17 and 18. How can you produce electricity?... right now!. The Law of Electric Charge. Like charges repel – push away Opposites attract. Electric Field. Charge It – How do we create charge?.

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Electricity and Magnetism Circuits Electromagnets

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  1. Electricity and MagnetismCircuitsElectromagnets Chapter 17 and 18

  2. How can you produce electricity?...right now!

  3. The Law of Electric Charge Like charges repel – push away Opposites attract

  4. Electric Field Charge It – How do we create charge? Friction – electrons are “wiped” from one object to another Conduction – electrons move through direct contact (a shock!) Induction – when charges are rearranged without direct contact • A region around a charged object in which an electric force is exerted on another charged object.

  5. What is an electric circuit? • A complete loop (begins and ends at the same place) through which electric charges flow.

  6. Voltage • The unit of measure for potential difference is the Volt (V) • Think 9 volt battery • The device that provides the potential difference is considered the voltage source;

  7. Current • The current is the rate at which a charge passes a given point • The unit for current is the ampere or Amp (symbol - A) • An amp is the amount of current that flows past a point in one second

  8. How does the flow begin? • Electrons in a circuit have potential energy • The potential energy of each charge is called electrical potential • In a battery, the electrical potential of one terminal is higher than the other terminal • The difference in this potential energy is called potential difference • This potential difference causes the loose electrons to be pulled away from their atoms and flow through the material

  9. The Essential Parts of a Circuit • An energy source – battery etc. • Wires – to carry the electric charge • Load – light bulb, radio etc.

  10. Switches • Some circuits in include a switch to open and close the circuit (turn it on and off) • Open – off (the loop is broken) • Closed – on (the loop is closed or complete)

  11. Types of Circuits • The parts of a circuit can be connected in different ways. The two main types are: • Series • Parallel

  12. Series Circuits • All parts are connected in a single loop • All loads in a series circuit share the same current

  13. Series Circuit • Will all bulbs burn with the same brightness? • Yes, all receiving the same electric current. • What will happen if I add a bulb? • They will all dim b/c they will receive less electric current. • What happens if one bulb burns out? • They will all go out, the loop is no longer complete.

  14. Parallel Circuit • A circuit in which loads are connected side by side • Current in a parallel circuit has more than one path • Each load receives the full amount of energy the energy source can provide (voltage) and they will use as much current as they need • Ex. 45 vs. 60 Watt light bulb

  15. Parallel Circuits • Will all bulbs burn with the same brightness? • No, it depends on their wattage. • What will happen if I add a bulb? • They will continue to burn with the same brightness. • What happens if one bulb burns out? • The remaining bulbs will stay lit.

  16. Questions to Consider: • Which circuit would be more useful in lighting a home or building? • Parallel, you want to be able to have the lights on in one room and off in another. • Which circuit is used in Christmas tree lights? • It depends, they used to be made in series, if one burned out all went out. Nowadays many are made in parallel so the remaining bulbs will continue to burn. • Why are series circuits useful? • Burglar alarms • What drawbacks are there in using parallel circuits?

  17. How does a compass work? • It is a magnet that works, moving from its north/south orientation only when it is no longer aligned with the earth’s poles • A man, Hans Oersted, found that when a compass is held near a wire that is passing electric current the compass would move even if it was still aligned with the poles.

  18. What is a solenoid? • Electricity and magnetism are closely related. This was first seen when a solenoid was developed. • A solenoid is simply a coil of wire that when current is flowing through it will generate a magnetic field.

  19. Electromagnet: • A stronger version of the solenoid! • It creates atemporary magnet when a current-carrying wire coil surrounds a magnetic metal core. • Useful because they can be turned off • Adding and removing coils can increase or decrease strength

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