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2012-12-06 13:44:36
current atom static potential difference

Unit P2 Revision
Show Answers:

  1. What are atoms?
    Atoms are basic particles from which all matter is made up
  2. What is an atom made up of?
    Protons, neutrons and electrons
  3. What are the masses of protons, neutrons and electrons?
    1 1 and 1/2000 respectively
  4. Materials that allow electricity to flow through them are called . . .
    electrical conductors eg.metal
  5. Materials that do not allow electricity to flow through them are called . . .
    electrical insulators eg.plastic
  6. When can an insulator become charged?
    When there is static electricity
  7. When does electric charge (static) build?
    When electrons (which have a negative charge) are rubbed off one material or onto another
  8. The material that recives electrons becomes...
    negatively charged
  9. The material that loses electrons becomes...
    positively charged
  10. Give three examples of common electrostatic phenomena
    any three from lightning, charges on synthetic fabrics, shocks from car doors or negatively charged balloons
  11. Explain how a laser printer works
    an image of the page to be copied is projected onto an electrically charged plate (+ve) Light causees charge to leak away leaving an electrostatic impression on the page. The impression attracts specks of black powder (of opposite charge) and heat is used to fix the final image
  12. Explain how electrostatic painting works
    The car panel is given a negative charge and sprayed with positively charged powder paint. The paint spreads out because the positive charges repel each other and are attracted to the negatively charged panel
  13. give an example of when unsafe static needs to be discharged
    filling aircraft fuel tanks
  14. what is earthing
    earthing allows constant safe discharge to occur, to equalise the imbalance of electrons between the two objects. When earthing occurs electrons flow from one body to the other to remove the imbalance
  15. What does electric current need to flow?
    A compete circuit
  16. The flow of electrons in a circuit is from . . .
    -ve to +ve (although we draw the current flow in a circuit from positive to negative)
  17. How do you work out charge?
    Charge (coulombs) = Current (amperes) X Time (seconds)
  18. Cells and batteries are sources of ______ current
  19. What is direct current?
    Current that flows in one direction only
  20. What is an alternative name for voltage?
    potential difference
  21. when current is flowing _____ is transferred from the cell to the circuit components
  22. the greater the potential difference the greater the _____ ____ and the greater the _____
    electron flow and current
  23. Potential difference is the energy (in joules ) that is transferred per unit charge (in coulombs) that passes through a source or component Formula...
    Volt = Joule/coulomb
  24. Current is measured . . .
    in amperes (amps) using an ammeter
  25. one millamp = ____ amps
    0.001 (one thousandth of)
  26. At any point in a series circuit the rate of electron flow will be __ ___ so the current and ammeter readings will be __ ___
    the same
  27. ammeters must be connected in
  28. voltmeters must be connected in
  29. In a circuit the current leaving the battery or the cell is the same as ___ ____ ____
    the current returning . Because electrons that make the current cannot leave the circuit.