2. Electrical symbols Plug problems Earthing Circuit breakers Electrical safety a.c. theory

3. previous next smart You should know all these by name and what they do!

4. previous next smart Adding these in series will decrease the current

5. previous next smart It’s graph curves as it gets hotter

6. previous next smart This one is open

7. previous next smart You choose the one above the current That should be flowing normally

8. V previous next smart Connect in parallel to measure the pd

9. previous next smart Provides a pd

10. previous next smart Low resistance when connected the right way round but no current will flow when it is the wrong way round

11. previous next smart Increasing light levels makes this have a lower resistance

12. previous next smart Increasing the temperature makes this devices resistance go down

13. previous next smart Changing its value increases and decreases the current

14. A previous next smart Connected in series to measure the current

15. previous next smart More than 1 cell is called a ________

16. previous next smart This one is closed

17. 1 fixed resistor 2 lamp 3 open switch 4 fuse 5 voltmeter 6 cell 7 diode 8 LDR 9 thermistor 10 variable resistor 11 ammeter 12 battery 13 closed switch

18. previous next smart

19. Plugs are a simple and safe way of connecting things to a mains circuit. In Britain the square- pin fused plug is the most commonly used type. When wiring a plug, check that: The wires are connected to the correct terminals: Brown to Live Blue to Neutral Yellow and green to Earth There are no loose strands of wire The cable is held firmly by the grip A fuse of the correct value is fitted previous next smart

20. What is wrong with these plugs? previous next smart

21. L N E previous next smart

22. L N E previous next smart

23. L N E previous next smart

24. L N E previous next smart

25. L N E previous next smart

26. L N E previous next smart

27. L N E previous next smart

28. L N E previous next smart

29. L N E previous next smart

30. L N E previous next smart

31. previous next smart

32. When you plug in an electrical device, you are connecting it into a circuit. The circuit hasn’t got a battery in it. But the mains Supplying electricity which Keeps changing direction. We call this an alternating current

33. Insulated cable fuse Live Neutral Earth 230V a.c. previous next smart

34. The ________ wire has a brown covering The ________ wire is a safety wire The ________ wire goes alternately + and – The ________ wire has a blue covering The ________ wire has a green and yellow covering

35. The live terminal of the mains supply between a positive and negative voltage with respect to the terminal. The neutral terminal stays at a voltage close to with respect to earth. previous next smart Higher level

36. answers live neutral earth Higher level Alternates Neutral zero

37. previous next smart

38. The neutral wire is kept at zero potential. The live wire potential alternates (changes) from positive to negative. This causes an alternating potential difference (p.d.) 0 0 p.d. (volt) volts +3380-3380+3380-3380 current previous next smart

39. previous next smart

40. fuse Earth A fault, such as the live wire touching the metal case can be dangerous. Earthing the case provides a low resistance path so a large current flows to earth, melts the fuse, breaks the circuit and stops the current. previous next smart

41. previous next smart

42. Normal current Large surge of current Push down to reset after the fault has been corrected previous next smart This coil of wire wrapped round a piece of iron is an electromagnet which gets strong enough to attract the rocker when there is a surge of current Iron rocker