1. U9A1: Introduction to Current Electricity (Part 1)

2. Part 1: What is an Electrical Circuit? Unbroken, no gaps Pathway for mobile electrons to move Contains Mobile Electrons

3. Question 1: What is an electrical circuit? Part 1: What is an Electrical Circuit? Question 2: Is this copper bracelet a circuit? Justify. Question 3: Is this gold bracelet a circuit? Justify.

4. Part 1: Useless vs. Useful Circuits Question 4: Just because a circuit meets the technical definition of a circuit doesn’t mean it is a useful circuit. Compare the two circuits shown below. Which one is useful (as a circuit) and which one is useless? What is the useful circuit doing? What does the useful circuit have that the useless one doesn’t?

5. Part 1: What Do All Useful Circuits Do? Transfer Energy!! Energy Here Transferred Here

6. Part 1: Current Electricity Transfers Energy Question 5: According to the state of Washington, our local power company, Puget Sound Energy, generates about 40% from hydroelectric sources and 25% from coal-fired power plants. Do some quick research online to answer the following questions: Identify the location of one of the hydroelectric dams used by PSE. Determine the distance from this dam to Renton. Identify the location of the coal-fired power plant used by PSE. Determine the distance from power plant to Renton.

7. Part 2: Introduction to Phet’s Virtual Circuit Lab From our class website, open the “Electric Circuit Virtual Lab” simulation. If successful, you will see the screen below (sometimes it takes a while to load):

8. Part 2: Practice Building Circuits in the Virtual Lab Circuit 1: In the simulation, build the circuit shown here. When you are done, move on to the next slide.

9. Part 2: What’s Moving in The Circuit? Question 1: In the virtual circuit lab, the blue spheres represent charge. Let’s get more specific than the generic term “charge.” What exactly do the blue spheres represent? Question 2: Let’s use the virtual circuit lab to check out the “Source of Charge” model for the battery. Open and close the switch in the circuit several times, observing the blue spheres (i.e., charge) as you do so. The virtual circuit does entirely not support the “Battery is the Source of Charge” model. Why part of the model is inconsistent with the virtual circuit? The virtual circuit is consistent with part of the “Battery as the Source of Charge” model. In what way is it consistent. What’s the Job of the Battery (Round 1): The “Source of Charge” Model Many people believe the role of a battery in a circuit is to provide charge to a circuit. For example, when a battery is connected to wires and light bulbs, they believe, charge leaves the battery and flows through the wires (and maybe the bulbs), causing the bulbs to light. When a switch in the circuit is opened, charge flows back into battery.

10. Question 3: Look closely at the photos above. What part of the lightbulb actually lights? Why do you think this part of the bulb emits light? Part 2: What’s Moving in The Circuit? Incandescent Light Bulbs Until about 10 years ago, light bulbs in a typical home were all incandescent bulbs. Although they are rapidly being displaced by LED’s and CFB’s, they still serve as a valuable learning tool for circuits. Question 4: Look closely at the bulb in the circuit, both when the switch is open and when it is closed. Based on your observations, is the light bulb part of the circuit? What is the evidence?

11. Part 2: What’s Moving in The Circuit? Question 5: What do you think the charge moving the lightbulb does to make the filament emit visible light (i.e., glow)? Question 6: Suppose the bulb in the circuit is a 5-watt light bulb. How much energy does the bulb emit per second? How much energy do you think the battery provides to the circuit each second? Justify.