1. Can you stick the sheet in?

2. Stand up!

3. Electricity

4. ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺

5. ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ cell energy electron lamp

6. ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ cell energy electron lamp Can you copy this please?

7. Today’s lesson Understand that current is the rate of flow of charge Recall and use: Q = It Looking at current in different circuits

8. Electrons ☺ Hi, I’m Eleanor the electron.

9. Coulomb of charge (electrons) Think of it as a “bag of electrons” (containing 6000000000000000000 electrons!) ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺

10. Coulomb of charge (electrons) Think of it as a “bag of electrons” (containing 6000000000000000000 electrons!) ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ Can you copy this please?

11. Current The number of Coulombs flowing past a point in the circuit every second. I = Q/t ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ A I’m counting how many coulombs of electrons go past me every second 1 Amp = 1 coulomb per second

12. Current The number of Coulombs flowing past a point in the circuit every second. I = Q/t ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ A I’m counting how many coulombs of electrons go past me every second 1 Amp = 1 coulomb per second Can you copy this please?

13. ☺ Let’s build some circuits!

14. In a series circuit Current is the same at any point in the circuit 2.5 A

15. In a series circuit Current is the same at any point in the circuit 2.5 A ☺ Can you copy this please?

16. In a parallel circuit The current splits (total current stays the same) 2.5 A 1.25 A

17. In a parallel circuit The current splits (total current stays the same) 2.5 A 1.25 A ☺ Can you copy this please?

18. Milliamps! 1 A = 1000 mA 1 mA = ?

19. Milliamps! 1 A = 1000 mA 1 mA = 0.001 A

20. Today’s lesson Understand that voltage is the number of joules per coulomb transferred Looking at voltage in different circuits

21. Stand up!

22. Voltage(emf) ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ V I’m checking the difference in energy (per coulomb) between the 2 red arrows 1 Volt = 1 Joule per coulomb

23. Voltage (p.d.) ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ V I’m checking the difference in energy (per coulomb) before and after the lamp 1 Volt = 1 Joule per coulomb

24. Voltage Voltage is the amount of energy transferred (changed) per coulomb of charge.

25. Let’s build some circuits! ☺

26. Stand up!

27. In a series circuit The sum of the voltages across the lamps equals the voltage across the cells 9 V 3 V

28. In a series circuit The sum of the voltages across the lamps equals the voltage across the cells 9 V 3 V ☺ Can you copy this please?

29. Stand up!

30. In a parallel circuit In a simple parallel circuit, voltage across each lamp equals the voltage across the cells 5 V

31. In a parallel circuit In a simple parallel circuit, voltage across each lamp equals the voltage across the cells 5 V ☺ Can you copy this please?

32. Today’s lesson Understand the term resistance Recall and use: V =IR

33. Stand up!

34. Resistance Measures how difficult it is for current to flow. Measured in Ohms (Ω) VA Resistance = voltage/currentR = V/I

35. Resistance Measures how difficult it is for current to flow. Measured in Ohms (Ω) VA Resistance = voltage/currentR = V/I ☺ Can you copy this please?

36. Ohm’s Law V = IR V R I X

37. Let’s measure a resistance!

38. Resistance of a lamp AV Resistance = voltage/currentR = V/I Vary the voltage and current using a variable resistor (rheostat). Plot a graph of resistance against current

39. Resistance of a lamp V(V)I(A)R(Ω) I(A) R(Ω)

40. Homework! Read pages 176 and 177 Answer questions on page 177 Due Wednesday 25 th November

41. Resistance of a lamp As the current in a lamp increases, it gets hotter, and its resistance increases. Why?

42. Resistance of a lamp As the current in a lamp increases, it gets hotter, and its resistance increases. Copy please.

43. Let’s try some resistance questions

44. Today’s lesson Understand the term power Recall and use: P =VI Recall and use E = VIt

45. Power The amount of energy used by a device per second, measured in Watts (Joules per second) VA Power = voltage x currentP = VI

46. Power The amount of energy used by a device per second, measured in Watts (Joules per second) VA Power = voltage x currentP = VI ☺ Can you copy this please?

47. Power of a lamp AV Power = voltage x currentP = VI Measure the power of the lamp at it’s operating voltage. What is the electrical energy being turned into?

48. Example A 200 W television is plugged into the 110V mains. What is the current in the television? P I V X

49. Example A 200 W television is plugged into the 110V mains. What is the current in the television? I = P/V = 200/110 = 1.8A P I V X

50. Example A kettle uses 240V and 8A. What is its power? P I V X

51. Example A kettle uses 240V and 8A. What is its power? P = VI = 240x8 = 1920W (=1.9kW) P I V X

52. Remember Power is the amount of energy used by a device per second, measured in Watts (Joules per second) VA Power = voltage x currentP = VI

53. Total energy So the total energy transformed by a lamp is the power (J/s) times the time the lamp is on for in seconds, E = VIt E = energy transformed (J) V = Voltage (also called p.d.) I = current (A) t = time (s)

54. Example A kettle uses 240V and 8A. What is its power? P = VI = 240x8 = 1920W (=1.9kW) How much energy does the kettle use in 5 minutes? P I V X

55. Example A kettle uses 240V and 8A. What is its power? P = VI = 240x8 = 1920W (=1.9kW) How much energy does the kettle use in 5 minutes? E = VIt = 240x8x300 = 576000 J P I V X

56. Simple!

57. Let’s try some questions!