Chiefly charge - igcse physics

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A presentation on Static Electricity based on the Edexcel IGCSE syllabus

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  • Welcome to nothingnerdy’s presentation on Everything Electric. Part 1: Chiefly Charge\n
  • In electricity, there are two groups of materials: those which conduct electricity and those which don’t. In fact, it’s more accurate to say that most materials will conduct if there is enough electrical energy. So you could say that an insulator is actually a bad conductor. This circuit shows how you can test substances for how well they conduct electricity. Different materials are placed in the gap in the circuit: a paperclip, penny, eraser or human hand.\n
  • Here are the results of a real experiment: the conducting materials, mostly metals but also graphite, are on the left and the insulators (or bad conductors) including plastic, wood and paper are on the right.\n
  • Before we talk about electric circuits, let’s look at the way in which electric charges can be given to materials. Rubbing certain materials can cause sparks, for example a balloon rubbed on wool. This is called charging by friction. The balloon is an insulator and a negative charge created by friction will just sit on it since it cannot flow on an insulator. An electric charge on a conductor, such as a human body, will spread all over it and will escape unless the body is insulated from contact with other conductors.\n
  • There are two types of electric charge, positive and negative. Charge differences in most solids are caused by the movement of negative electrons from atoms. The positive part of the atom, the nucleus, does not move. This means that a positive charge is caused when a material loses electrons. Static electric charges can be explained by the movement of electrons.\n
  • Electric charges exert forces on each other. There are two possible interactions, attraction and repulsion. Two positive charges will repel each other with equal and opposite forces (even if the charges aren’t equal); the same is true of two negative charges. Opposite charges attract each other.\n
  • A charged balloon will stick to a wall even though the wall is not charged. This is because the negative charge on the balloon repels the electrons in the wall. The nuclei do not move. This means that the surface of the wall is now positive so the two objects are attracted to each other.\n
  • The vdGG transfers electric charge from the rotating belt to the insulated metal dome where it can be used to create large sparks when it\n
  • Sometimes, large amounts of electric charge accumulate. This can can cause electric shocks or explosions if there is a spark near inflammable gases. Aircraft can gain large electric charges so, to avoid an explosion during refuelling, the charge must be discharged by connecting the aircraft to the ground using a cable.\n
  • The forces between charged materials can be used in various devices. In the photocopier, a negative charge is placed on the surface of a metal drum. Light from the image to be copied removes charge from parts of the drum so that there is now an image in charge on the drum. Positively charged toner sticks to the negative charge image on the drum. The image on the drum is now transferred to negatively charged paper.\n
  • A jet of ink drops is given an electric charge and then passes between two metal plates carrying a charge so that the force on the drops changes the direction of the jet of ink and it writes the image.\n
  • \n
  • Welcome to nothingnerdy’s presentation on Everything Electric. Part 1: Chiefly Charge\n
  • Chiefly charge - igcse physics

    1. 1. presentsa production Everything Electric Episode 1 Chiefly Charge
    2. 2. Conductors and Insulators Electric charge moves around a circuitYou can build this circuit and test different conducting materials at http://phet.colorado.edu/en/simulation/circuit-construction-kit-ac
    3. 3. Conductors and Insulators Insulators are bad conductors Image source: Sandaig Primary School
    4. 4. Charging by friction An object can be given an electric charge if it is rubbed against another substance. This will work for either a conductorLink: Balloons sim at PHET which is insulated from the ground eg you wearing shoes. Beware shocks! Link: Travoltage sim at PHET ...or an insulator eg a balloon Many more brilliant simulations at: http://phet.colorado.edu
    5. 5. Electric charge is carried by electrons Reminder: electrons have a negative charge Although there are two types of charge, positive and negative, in most materials only the negative electrons can move. So a positively charged object eg this sweater, has lost electrons. The balloon has gained Link: Balloons sim at PHET electrons.
    6. 6. Attraction and repulsion + + + - - - Two electric charges exert equal and oppositeforces on each other. Similar charges repel each other and opposite charges attract each other.
    7. 7. Electrostatic inductionQ: Why does the balloon stick to the wall? The electrons in the atoms in the wall can move but the positive charges cannot. The negative charge on the balloon repels the electrons in the wall but the positive nuclei do not move. The surface of the wall becomes positively charged *by induction*. A: The negative balloon is attracted to the induced positive charge on the surface. *the total charge on the wall is still zero*Link: Balloons sim at PHET
    8. 8. van de Graaff generator A device which creates a large static electric charge on an insulated metal dome.Image: Dake @ wikipedia
    9. 9. The dangers of static electricityLarge amounts of static electricity cause dangerous sparks whichcan hurt you or ignite inflammable materials.When refuelling aircraft, any static electricity gained during flightmust be discharged using a cable connected to the earth. © Copyright Richard Smith and licensed for reuse underImage source: John Evans Sons, Inc. this Creative Commons Licence.
    10. 10. The Photocopier1 Negative electric charge placed onsurface of metal drum.2 Light from white parts of imageremoves negative charge.3 Positively charged toner sticks tonegative charge on drum.4 Toner transferred from drum tonegatively charged paper.Image credit:Yzmo on wikipedia.org
    11. 11. The inkjet printer The stream of ink droplets is electrically charged. It is deflected up and down by varying static charge on the deflection plates.Image credit: The free dictionary
    12. 12. More uses of electric charge Image: US National Archive @ flickr Image: Lindenpainting.comElectrostatic painting The paintand object have opposite charges. Electrostatic precipitation Smoke particles are given a charge and removed from the chimney by an opposite charge.
    13. 13. a production MUCH MORE AThttp://nothingnerdy.wikispaces.com http://nothingnerdy.wikispaces.com/ELECTRIC+CHARGE

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