Using Electricity

Card Set Information

Using Electricity
2011-01-30 06:11:46
Physics Using Electricity

Standard Grade Physics - Using Electricity
Show Answers:

  1. What kind of appliances usually have high power ratings?
    Appliances which give out heat
  2. What is the purpose of a fuse?
    To protect the flex.
  3. What colour is the live wire?
  4. What colour is the neutral wire?
  5. What colour is the earth wire?
    Green and Yellow
  6. Where are the wires located in a plug?
    • The BRown wire goes in the Bottom Right
    • The BLue wire goes in the Bottom Left
    • The green and yellow wire goes in the top
  7. What does the live wire do?
    Carries the electrical energy to the appliance
  8. What does the neutral wire do?
    Complete the ciruit
  9. What does the earth wire do?
    Acts as a safety device
  10. When might appliances not require an earth wire?
    If they have the double insulation symbol
  11. Why is it dangerous if the live and neutral are reversed in a plug?
    As if the appliance is off or the circuit is broken the appliance is still live!!
  12. What is direct current?
    Current that flows in one direction
  13. The mains supply is ____?
  14. A battery supply is _____?
  15. What is the mains voltage?
  16. Electrons are _______ to move in a conductor?
  17. What do we measure current in?
    Amperes (A)
  18. What do we measure voltage in?
    Volts (V)
  19. What do we measure resistance in?
    Ohms (Ω)
  20. How do we link voltage, current and resistance together?
    V = IR
  21. What is charge measured in?
    Coulombs (C)
  22. What is the formula for charge?
    Q = It
  23. The current in a series ciruit is ________ at all points?
    the same
  24. In a parallel circuit, the sum of the currents in the parallel branches is ______ to the current drawn from the supply?
  25. In a series circuit, the sum of the voltages across the components is ________ to the voltage of the supply?
  26. In a parallel circuit, the voltage across each branch is ______?
    the same
  27. How do you work out resistance in a series circuit?
    Rs = R1 + R2 + R3 .....
  28. How do you work out resistance in a parallel circuit?
    1/Rp = 1/R1 + 1/R2 .....
  29. What is an open ciruit?
    A circuit with a loose or broken wire. The open circuit resistance on an ohmmeter shows ∞ Ω
  30. What is a short circuit?
    A circuit with two wires touching or being crossed by a loose wire. Short circuit resistance = 0 Ω
  31. In a filament lamp the energy transformation takes place in the _____?
  32. In a discharge tube the energy transformation takes place in the _____?
  33. Why is the discharge tube more effecient than the filament lamp?
    As more energy is transformed into light
  34. The energy transformation in an electric heater takes place in the ______?
  35. What are the advantages of using a ring main circuit instead of a lighting circuit?
    • Carries more current
    • Uses less copper - so is less expensive
  36. Why may a circuit breaker be used instead of a fuse?
    • They are easy to reset
    • Cannot replace them with the wrong value (danger of a fuse)
    • They are more sensitive - they flip quickly
  37. A ________ exists around a current carrying wire?
    magnetic field
  38. What is the purpose of brushes in a motor?
    They allow electrical connection to a moving contact
  39. Why are carbon brushes good?
    • They are cheap, good conductors
    • They are easily replaced if they wear away completely
  40. What is the purpose of the commutator in a motor?
    It keeps the motor turning in one direction
  41. Why are multi-section commutators good?
    They make the motor smoother and more powerful
  42. Why are stationary field coils good?
    They make the motor lighter and cheaper
  43. How can you turn the motor quicker?
    • Increase:
    • the size of the current
    • the number of turns of the coil
    • the magnetic field strength
  44. Give two examples of uses of electromagnets
    • Electric Bell
    • Relay Switch