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GCSE Physics P5 (OCR)

Usman Rauf Physics GCSE Inglés 61 fichas

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  1. 1What happens when two objects are rubbed together?They become charged because electrons are transferred from one object to another.
  2. 2Objects with similar charges ______. Objects with opposite charges ________.Repel
    Attract
  3. 3Why does a charged rod pick up pieces of paper?If a negatively charged rod comes near, it repels negative charges in the paper to the far end. This leaves a surplus of positive charges at the near end. The attraction between these charges and the negatively charged rod is stronger than the repulsion between the negative charges in the paper and the rod.
  4. 4Are electrons negatively or positively charged?Negatively
  5. 5What is electric current?A flow of charge
  6. 6What is electric current measured in?Amperes
  7. 7What is an electric current in metallic conductors?A movement of free electrons that are present throughout such materials.
  8. 8In metal conductors there are ______ charges free to move. In an insulator there are ____ charges free to move.Many
    Few
  9. 9The ______ the voltage of the battery in a circuit, the ______ the current.Larger
    Bigger
  10. 10Components _______ the flow of charge between them.Resist.
    (Eg. Resistors, lamps, motors)
  11. 11The _______ the resistance in a circuit, the _______ the current will be.Larger
    Smaller
  12. 12Why can the resistance of connecting wires usually be ignored?Because it is so small.
  13. 13What happens when electric charge flows through a component?Work is done by the power supply, and energy is transferred from it to the component and its surroundings.
  14. 14What is power?A measure of the rate at which an electrical power supply transfers energy to an appliance of device and its surroundings.
  15. 15What is power measured in?Watts (W)
  16. 16Power = _________ x _________Voltage x Current
  17. 17What happens to resistors when an electric current runs through them?They get hotter. This is caused by collisions between the moving charges and stationary ions in the wire.
  18. 18What effect does this heating have on a lamp filament?It makes it hot enough to glow.
  19. 19How does the resistant of and LDR vary with light intensity?As light intensity increases, resistance decreases.
  20. 20How does the resistance of a thermistor vary with temperature?Resistance decreases as temperature increases.
  21. 21What happens to the resistance if there are two (or more) resistors in series?The resistance increases because the battery has to move charges through both of them.
  22. 22What happens to the resistance if there are two (or more) resistors in parallel?The resistance is decreased because there are more paths for charges to move along.
  23. 23What is resistance measured in?Ohms
  24. 24Resistance = _______ / _________Voltage / Current
  25. 25How does the current through a component vary with voltage across it when the resistance stays the same?The higher the voltage, the higher the current. If current increases by one, then voltage increases by two.
  26. 26How should a voltmeter be connected to measure the potential difference between any two chosen points?It should be connected at both of the chosen points.
  27. 27What is the voltage across a battery the measure of?The 'push' of the battery on the charges in the circuit.
  28. 28What is potential difference?Another term for voltage.
    The work done when a coulomb of charge passes between two points.
  29. 29How does the potential difference relate to the work done by a charge?The bigger the charge, the bigger the potential difference.
    (Because water is being pumped higher, so it has further to fall.)
  30. 30How does adding batteries in series effect the potential difference?The potential difference would increase.
  31. 31How does adding batteries in parallel effect the potential difference?It does not change.
  32. 32What happens to the current when two (or more) components are added in series to a battery?It stays the same through each component.
  33. 33What happens to the potential difference when two (or more) components are added in series to a battery?The potential differences across each component adds up to the potential difference across the battery because the work done on each unit of charge by the battery must equal the work done by it on the circuit components.
  34. 34What happens to the potential difference across a component when two (or more) components are added in series to a battery?The potential difference is largest across the component with the greatest resistance because more work is done by the charge moving through a large resistance than through a small one.
  35. 35What happens to the potential difference if the resistance of one component is changed when two (or more) components are added in series to a battery?It will results in a change in the potential difference across all of the components.
  36. 36What happens to the potential difference when two (or more) components are added in parallel to a battery?The potential difference across each component is equal to the potential difference of the battery.
  37. 37What happens to the current when two (or more) components are added in series to a battery?It is the same.
  38. 38What is mains electricity produce by?Generators
  39. 39How do generators produce a voltage?By electromagnetic induction
  40. 40What happens when a magnet is moving into a coil of wire?A voltage is induced across the ends of the coil, which causes an electric current in the circuit.
  41. 41What happens if the magnet is moving out of the coil?There is a voltage induced in the opposite direction.
  42. 42What happens if the ends of the coil are connected?A current will flow around the circuit.
  43. 43Describe how transformers are constructed.Two coils of wire are wound on an iron core.
  44. 44What will a changing current in one coil of a transformer cause?A changing magnetic field in the iron core, which in turn will induce a changing potential difference across the other transformer coil.
  45. 45What can a transformer do?Alternate the size of an alternating voltage.
  46. 46Vs/Vp = Ns/NpVoltage across secondary coil / Voltage across primary coil
    =Number of turns on secondary coil/ Number of turns on primary coil
  47. 47How is a magnet or electromagnet rotated within a coil of wire to produce a voltage across the ends of the coil?While the magnet moves into the coil, the magnetic field around the magnet changes. Magnetic field lines are 'cutting' the coil. This causes a potential difference (a voltage) across the coil.
  48. 48How can the size of this voltage be increased?- Moving the magnet in and out more quickly
    - Using a stronger magnet
    - Increasing the number of turns on the coil
    - Placing an iron core inside the coil
  49. 49How does the induced voltage across the coil of an a.c. generator change during each revolution of the magnet?The voltage and current change direction every half turn of the magnet.
  50. 50What is direct current? What is alternating current?D.C = The current is always in the same direction (eg. a battery).
    A.C. = The current changes direction.
  51. 51Is mains electricity an a.c supply or a d.c supply?A.C
  52. 52Why is A.C used for mains electricity?Because it is easier to generate than d.c. and it is easier and simpler to distribute over long distances.
  53. 53What voltage is mains domestic supply in the UK?230 volts.
  54. 54How can the size of the alternating voltage produced by a generator be increased?- Using a stronger rotating magnet
    - Rotating the magnet faster
    - Using a fixed coil with more turns
    - Putting an iron core inside the fixed coil
  55. 55A _______-______ ____ can exert a force on a permanent ______, or another _______-______ ______ nearby.Current-Carrying Wire
    Magnet
    Current-Carrying Wire
  56. 56To make a motor, where is the current-carrying wire placed?In a magnetic field whose lines of force are at right angles to the wire.
  57. 57When placed here, what does the wire experience?A force at right angles to both the current direction and the lines of force in the field.
  58. 58What happens if the current-carrying wire is parallel to the lines of force of a magnetic field?It experiences no force.
  59. 59How can the motor effect result in a turning force on a rectangular current-carrying coil placed in a uniform magnetic field?The currents in the two sides of the forces are at right angles to the magnetic field lines, so there will be forces on them. One force is up an the other down because the currents in the two sides of the coil are in opposite directions. The effect of these forces is to make the coil rotate.
  60. 60What can the motor effect be used to produce?Continuous rotation of the coil, by using a commutator to ensure that the direction of the current in the coil is reversed at an appropriate point in each rotation.
  61. 61How does a commutator work?It is fixed to the coil and rotates with it. Ad the coil rotates, each half of the split ring touches one brush for half a turn, and the other brush for the next. So the current direction in the coil is reversed twice every turn - changing the direction of the magnetic forces, and keeping the coil rotating.

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GCSE Physics Fichas sobre GCSE Physics P5 (OCR), creado por Usman Rauf el 16/04/2015.
Creado por
Usman Rauf
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  • Creado por Josh Price · 16 abr 2015
  • Copiado por Usman Rauf · 16 abr 2015
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