cell

1. ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ cell energy electron lamp

2. Coulomb of charge (electrons) Think of it as a “bag of electrons” (containing 6250000000000000000 electrons!) ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺ ☺

3. A ☺ ☺ ☺ ☺ ☺ I’m counting how many coulombs of electrons go past me every second Current ☺ ☺ The number of Coulombs flowing past a point in the circuit every second. ☺ ☺ ☺ ☺ 1 Amp = 1 coulomb per second

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

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

6. Draw the sentence • Electricity is the flow of electrons. • We measure the quantity of electrons in Coulombs. • One Amp means one Coulomb of electrons flows round every second. • The electrons carry energy from the cell to the lamp. • The electrons then return to the cell to get more energy. • The electrons are NOT used by the lamp. • Voltage measures the amount of energy each coulomb receives or gives. • Physics is the most important subject Science subject!

7. Cell and battery of cells

8. d.c. power supply

9. a.c. power supply

10. Lamp

11. Resistance of a filament lamp • Resistance increases as the current increases (because the wire gets hot) Voltage Current

12. open switch

13. Ammeter

14. Voltmeter

15. Resistor

16. Variable resistor (rheostat)

17. Bell/buzzer

18. Thermistor • Resistance decreases with increasing temperature Resistance Temp

19. Light-dependent resistor (LDR) • High resistance in the dark but a low resistance in light

20. Diode • Allows current to flow in one direction only (from + to – in the direction of the “arrow)

21. A ☺ ☺ ☺ ☺ ☺ I’m counting how many coulombs of electrons go past me every second Current ☺ ☺ The number of Coulombs flowing past a point in the circuit every second. ☺ ☺ ☺ Can you COPY the blue writing please? ☺ 1 Amp = 1 coulomb per second

22. Current I = Q/t Where I = current in Amps Q = charge (# of electrons) in Coulombs t = time in seconds

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

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

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

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

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

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

29. Voltage Voltage is the amount of energy transferred (changed) per coulomb of charge. 1 Volt = 1 Joule per coulomb A voltmeter connected across the component

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

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

32. V A Resistance Measures how difficult it is for current to flow. Measured in Ohms (Ω) Resistance = voltage/current R = V/I

33. V I R X Ohm’s Law • V = IR

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

35. V A Power The amount of energy used by a device per second, measured in Watts (Joules per second) Power = voltage x current P = VI

36. P V I X 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

37. 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)

38. P V I X 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

39. Alternating current • Current changes direction 50 times a second.

40. Fuse • Thin piece of wire which melts if the current is too high • If a fault develops, this thin piece of wire melts if the current is too high • Circuit breakers are sometimes used instead

41. Earth wire • Connects metal body of appliance to earth • If a live wire comes loose, current flows to earth and blows the fuse

42. Double insulation • Some appliances have no earth wire because they have a plastic outer case • The plastic case acts as an extra layer of insulation around the wires

43. Electrostatics 1. There are two types of electric charge (positive and negative) Hi! Hola!

44. Electrostatics 2. Opposites attract

45. Electrostatics 3. Static charges can be produced by the action of friction on an insulator Plastic, amber, glass, Perspex

46. Electrostatics 4. Electrons are negatively charged

47. Electrostaticshttp://phet.colorado.edu/sims/balloons/balloons_en.jnlpElectrostaticshttp://phet.colorado.edu/sims/balloons/balloons_en.jnlp 5. Objects are charged positive by the loss of electrons cloth

48. Electrostatics 6. Objects are charged negative by the gain of electrons Only electrons move, that’s why they call it electricity! cloth

49. ElectrostaticsYouTube - Refueling Fire Caused by Static Electricity 7. Static charges can be dangerous

50. Electrostatics 7. Static charges can be dangerousYouTube - Gas Station Fire, Static Electricity Starts a Flash Fire.