AQA Physics P3.3

The flashcards below were created by user BMH on FreezingBlue Flashcards.

  1. What sort of field is produced when a current flows through a wire
    • A magnetic field
    • Image Upload
  2. What is produced when a current flows through a wire in a magnetic field
    • A force. This is called the motor effect.
    • Image Upload Image UploadImage Upload
  3. How can the size of the force produced by the motor effect be increased?
    • Increasing the strength of the magnetic field,
    • Increasing the size of the current
  4. In Fleming’s left-hand rule, what does the second finger represent?
    • Current ( SeCond)
    • Image Upload
  5. In Fleming’s left-hand rule, what does the first finger represent?
    • Magnetic Field (First)
    • Image Upload
  6. In Fleming’s left-hand rule, what does the thumb represent?
    • Thrust (Thumb), or Movement (ThuMb) (both mean the same thing!)
    • Image Upload
  7. How can the direction of the force produced by the motor effect be reversed?
    • Changing the direction of the current, or
    • Changing the direction of the magnetic field
  8. What are the 3 ways that the strength of an electromagnet can be increased?
    • More turns of wire in the coil,
    • increasing the current,
    • adding an iron core inside the coil
  9. Name some uses of electromagnets
    • Separating steel and iron from other metals,
    • moving heavy pieces of iron and steel in a scrapyard,
    • loudspeaker coils,
    • relays,
    • circuit breakers
    • Image UploadImage UploadImage Upload
  10. What is a relay used for?
    • Using a low pd circuit to switch on a high pd circuit. (This makes it much safer to use)
    • Image Upload
  11. What does a circuit-breaker do?
    • Used to switch off current in a circuit if the current is too high (usually because of a fault)
    • Image Upload
  12. What is produced when a wire is moved in a magnetic field?
    A potential difference is induced in the wire. (This can be used to make current flow)
  13. What does an electrical transformer do?
    Changes the potential difference (voltage).

    A step-up transformer increases the pd. A step-down transformer reduces the pd.
  14. What are the two coils called in a transformer?
    • Primary and secondary coils
    • Image Upload
  15. What are the 3 components of a transformer?
    • Primary coil,
    • Secondary coil,
    • Iron core
    • Image Upload
  16. In the equation
    Image Upload

    what does Ns represent?
    The number of turns in the secondary coil
  17. Step-up transformers induce a larger pd in the secondary coil (output) than the primary coil (input). How can this be when the law of conservation of energy states that energy cannot be created or destroyed?
    Step-up transformers increase the pd in the secondary coil but also decrease the current.

    • As Power = voltage x current,
    • the overall power (and hence energy) remains the same.
  18. Transformers are less than 100% efficient. Where does the wasted energy go?
    • Heat
    • Image Upload
  19. Switch-mode transformers are more modern versions of transformers and use electronic circuits inside them. What are the advantages of this type of transformer?
    • Smaller,
    • lighter,
    • use very little power when no load is applied (such as when a mobile battery is left on charge but is fully charged)
    • Image Upload
Card Set:
AQA Physics P3.3
2015-03-13 18:09:09
AQA Physics P3

AQA Physics P3.3
Show Answers: