2. Static Electricity Circuits Part Deux Safety In the House 10 20 30 40 50

3. Question 1 - 10 What is electricity

4. Answer 1 – 10 Electricity is the set of physical phenomena associated with the presence and flow of electric charge.

5. Question 1 - 20 If you rub plastic and fur together what will happen, with respect to charge, to each of those substances?

6. Answer 1 – 20 Fur will loose electrons and become positively charged and plastic will gain electrons and become negatively charged.

7. Question 1 - 30 What is conductivity and how does an insulator differ from a conductor? – Be sure to include an example of the conductor and the insulator.

8. Answer 1 – 30 Conductivity – ability of materials to allow electrons to move freely in them – Insulator – solid, liquid or gas resisting flow of electrons – Conductor – solid, liquid or gas allowing flow of electrons

9. Question 1 - 40 If you were to bring a negatively charged balloon close to a wall. Explain, using two laws, what will happen to the charges in the wall.

10. Answer 1 – 40 Negative will move inward, positive will remain to hold balloon Law of Attraction and Repulsion – Opposites attract – Like charges repel

11. Question 1 - 50 What is an electroscope and how does it demonstrate induction?

12. Answer 1 – 50 Electroscope – detects static charge Induction – movement of electrons within a substance caused by a nearby charged object, without direct contact between the substance and the object.

13. Question 2 - 10 Draw and name three symbols from a schematic circuit diagram.

14. Answer 2 – 10

15. Question 2 - 20 What is an electrochemical cell? – How does an electrolyte differ from an electrode in an electrochemical cell?

16. Answer 2 – 20 A battery is a combination of electrochemical cells – Electrochemical cells are packages of chemicals that convert chemical energy into electrical energy – Electrolyte – liquid or paste that conducts electricity because it contains chemicals that form ions. – Electrodes – metal strips that react with the electrolyte – Chemical reaction allows electrons to collect on one of the electrodes making it negatively charged.

17. Question 2 - 30 Draw a schematic diagram for a circuit with a 9V battery, two equal resistors, a switch an ammeter and a voltmeter measuring current across one of the resistors indicating what the voltage would be.

18. Answer 2 – 30 Diagram

19. Question 2 - 40 How does a wet cell differ from a dry cell? Be sure to include examples.

20. Answer 2 – 40 Dry cell – uses a paste electrolyte Wet cell – uses a liquid electrolyte

21. Question 2 - 50 Please define current, voltage and resistance.

22. Answer 2 – 50 The difference in electrical potential energy between two points in a circuit is called the potential difference Electric Current is a measure of the amount of electric charge that passes a point in an electric circuit each second. Degree to which a substance opposes flow of electric current through it. – This resistance slows down the flow of electrons and therefore it slows down the current and converts electrical energy into other forms of energy

23. Question 3 - 10 How does a series circuit differ from a parallel circuit?

24. Answer 3 – 10 Parallel - Components are arranged so that electrons can flow along more than one path – A break does not affect all loads Components are arranged one after another in series – One light goes out, they all go out – Add more resistance and you decrease the current

25. Question 3 - 20 Draw a parallel circuit with a 9V battery, three resistors each with its own switch, an ammeter measuring current out of the second resistor and a voltmeter measuring the voltage across the third resistor.

26. Answer 3 – 20 Drawing

27. Question 3 - 30 What is Ohm’s Law

28. Answer 3 – 30 As long as temperature stays the same, V=IR

29. Question 3 - 40 A current of 2.3 A flows through a 50 ohm resistor that is connect to a battery. What is the voltage of the battery?

30. Answer 3 – 40 115 V

31. Question 3 - 50 A current of 675 mA runs through a resistor that is connected to a 120 V power supply. What is the resistance of the bulb?

32. Answer 3 – 50 177.78 ohms

33. Question 4 - 10 What is a short circuit?

34. Answer 4 – 10 Accidental low resistance connection between two points in a circuit, causing excess current flow. Electrical devices will not work and will be dangerous – heat or fire.

35. Question 4 - 20 Compare and contrast fuses and circuit breakers.

36. Answer 4 – 20 Fuse = safety device in an electrical circuit that has a low melting point, compared to wires. Circuit breaker = does the same thing but instead of melting, the wire heats up and bends which triggers a spring mechanism to turn off the electricity

37. Question 4 - 30 Identify two electrical safety devices involved with plugging in an appliance. – Think plug and appliance – Explain how they work.

38. Answer 4 – 30

39. Question 4 - 40 Why must you avoid frayed electrical cords.

40. Answer 4 – 40 Electric Shock…short circuit.

41. Question 4 - 50 You want to find the value of an unknown resistor however you have access to a multimeter. How could you figure it out?

42. Answer 4 – 50 R = V/I Use the ohmmeter function

43. Question 5 - 10 What does time of use (TOU) electricity billing mean?

44. Answer 5 – 10 Smart meters send usage of electricity on a house by house basis to the electric company so that the house gets charged the right amount

45. Question 5 - 20 If a kettle uses 1.5 kW per hour and you have it on for 15 minutes every day, how much does your energy cost per year. – Assume energy costs you $0.105/hour.

46. Answer 5 – 20 $14.37

47. Question 5 - 30 What is the percent efficiency of a bulb that has 1000 joules of energy going in but only 600 joules of energy coming out?

48. Answer 5 – 30 600/1000 x 100 = 60% efficient

49. Question 5 - 40 How does Energuide differ from Enerstar?

50. Answer 5 – 40 Energuide – average energy use in a month or year for an appliance compared to other similar appliances. Energy Star – means the appliance is one of the most efficient appliances in its class.

51. Question 5 - 50 What are 5 things you can do at home to reduce energy consumption, or at least reduce the cost of your energy bill.

52. Answer 5 – 50 OPEN