1. Warm Up: Where do electric charges come from?

2. Warm Up: Where do electric charges come from? Electric charges come from protons which are positive (+) and electrons which are negative (-)

5. There are 3 types of charging 1. Friction 2. Conduction 3. Induction

6. Friction When two neutral objects are rubbed against each other, one object may pull electrons away from the other creating one positive object and one negative object.

7. Conduction An object can be charged by touching it with another object that already has a charge. The resulting object will then have the same charge but weaker in strength than the original object.

8. Induction Objects do not touch (one is charged, one is neutral) Proximity of the charged object causes (induces) the charges in the neutral object to separate.

9. Examples https://phet.colorado.edu/sims/html/balloons-and- static-electricity/latest/balloons-and-static- electricity_en.html https://phet.colorado.edu/sims/html/balloons-and- static-electricity/latest/balloons-and-static- electricity_en.html https://www.youtube.com/watch?v=XT7edg_BAl4&no html5=False https://www.youtube.com/watch?v=XT7edg_BAl4&no html5=False

11. How is a circuit different from a trail in the forest? A trail may begin in one place and end in another. A circuit forms a loop, meaning it always begins and ends in the same place

13. What is a circuit? A complete, closed path through which electric charges flow

14. What are the parts of a circuit? A. an energy source B. a load C. wires to connect the parts together

16. What are examples of energy sources? ~ A battery, a photocell, a thermocouple, or an electric generator at a power plant

17. What is a load? Give examples ~ a device that uses electrical energy to do work ~Examples: light bulbs, appliances, televisions and motors

18. What are wires usually made of? ~conducting materials with a low resistance, such as copper

19. What is the purpose of the wires? to connect the parts of a circuit

20. What is a switch? used to open and close a circuit turn "on" a switch the circuit is ­closed allowing charges to flow through the circuit turn "off" a switch the circuit is open breaking the loop and not allowing charges to flow

21. Circuits Most~load circuits contain more than one ________ What are the two ways that different loads can be connected to the same circuit? A. Series B. parallel

22. Warm up: What does the term resistance mean in relation to electrical circuits

23. Types of Circuits Series A. all the parts are connected in a single loop B. charges only follow one path and must flow through each part C. all loads share the same current D. light bulbs in series = all lights glow with same brightness, if you add more lights then R of circuit increase & I decreases causing the light bulbs to be dimmer Parallel A. different loads are located on different branches B. charges follow more than one path C. loads do not share same current, but do have same voltage D. light bulbs in parallel = the full V of the battery is applied to each bulb causing each light to glow at full brightness, ~add more lights then each light bulb still glows at full brightness A. parts  B. Path  C. current  D. Example  Description

24. Types of Circuits Series - uses use a load as a switch = automatic doors at grocery store Christmas tree lights are in series wiring bank alarms Parallel - uses in your home each outlet has its own branch and its own on/off switch

25. Types of Circuits Series – advantages/disadvantages ~disadvantage in that all loads must be turned on and working or the series will not work ~disadvantage in homes if lamp was connected to tv (lamp doesn't work so tv doesn't work) ~advantage in wiring bank alarms (if one part goes off then the rest of the system goes off and alerts that there is reason for alarm) Parallel – advantages/disadvantages ~you can connect loads that required different currents to the same parallel circuit ~you can use one light or appliance at a time, even if another branch fails ~Ex. your lamp goes out but your tv stays on ~can overload it!

26. What type of circuits are most household circuits? ~most are parallel circuits with several loads attached to them ~the circuits break out from a breaker box or a fuse box that acts as the “electrical headquarters” for the building, each branch receives the standard 120 V

27. How can circuits fail? ~broken wires or water can cause electrical appliances to “short circuit”

28. What is a “short circuit” & why is it dangerous? ~these happen when charges bypass the loads in the circuit ~when the charges bypass the loads, the resistance of the circuit drops, and the current increases ~if the current increases too much, an electrical fire can result

29. What is another way that causes circuits to fail? ~if circuits are overloaded which means too many loads, or electrical devices, are attached to it ~each time you add a load to a parallel circuit, the entire load draws more current, which can lead to fire

30. What are the two most commonly used safety devices and where are they located? fuses and circuit breakers which are found in a fuse box or circuit box

31. How do fuses work? ~they contain a thin strip of metal in which the current flows ~if temperature is too high, the metal melts causing a break or gap in the circuit (this is called “blowing a fuse”) ~blown fuses must be replaced with new fuses

32. How do circuit breakers work? ~a switch that automatically opens if the current in the circuit is too high ~when current is too high, a strip of metal bends away from the wires in the circuit creating a gap ~Open circuit breakers can easily be closed by flipping a switch located inside the breaker box once the problem has been fixed

33. How to draw circuits

34. Draw a series circuit with one battery, one light and one switch

35. Draw a parallel circuit with three light bulbs, one switch and one battery. The switch should turn off all light bulbs

36. Draw a series circuit with four light bulbs, one switch and two batteries

37. Draw a parallel circuit with three light bulbs, one switch and one battery. The switch should turn off two light bulbs.

39. Warm Up: What is an analogy? Todays Agenda: 1. Warm-up 2. Voltage, Current, Resistance Article SSR - 10 min 3. Jig-Saw Article 4. Demo : https://phet.colorado.edu/sims/html/ohms- law/latest/ohms-law_en.htmlhttps://phet.colorado.edu/sims/html/ohms- law/latest/ohms-law_en.html 5. Practice Ohm’s Law questions

42. What is the current in a 10V circuit if the resistance is 2Ω?

43. What is the current in a 120V circuit if the resistance 20Ω?

44. What is the current in a 120V circuit if the resistance 10Ω?

45. What voltage is required to move 2A through 5Ω?

46. What voltage is required to move 2A through 10Ω?

47. What voltage is required to move 2A through 20Ω?

48. What is the resistance of a circuit with 20V and 2A?

49. What is the resistance of a circuit wit 120V and 1A?

50. What is the resistance of a circuit with 120V and 10A?