1. TODAY’S OUTCOMES: - Review the concepts and definitions of current, voltage, power, and energy. - Investigate the relationship between power, current, and voltage. - Use the data we collected tracking the sun’s shadow to determine how it moves across the sky. ELECTRICITY SUN AND MOON

2. GRADING OF VOLTAGE 5 points: 3 points - 1 - Comparison of siphon to battery 1 - Mentioning height difference 1 - Getting aquarium answer right 2 points - 1 - Well thought out, consistent answer 1 - Energy or power

3. In a water-siphon system, the analogous rule would be that the overall height between the source water and the dump location, regardless of the path or shape of the hose, is what determines the flow rate. 12. What would be the water analogy to the rule you gave (Q3)? Suppose you wanted to siphon water out of a fish tank quickly: what does the rule tell you? Sample Q3 rule: Brightness of bulbs in a series circuit increases with the number of batteries and decreases with the number of bulbs, and is not dependent on the sequence of the elements.

4. VISUALLY, LET’S COMPARE EXAMPLES + + – – 2 batteries 1 2 – + 1 battery 1 VOLTAGE ⇔ Height of the siphon system CURRENT ⇔ Flow rate of the siphon system

5. VISUALLY, LET’S COMPARE EXAMPLES + + – – 2 batteries + + – – + +– – A BC D + + – – A B C D AB C D A B C D Height determines the flow rate; the placement of obstacles does not matter. Both systems (above, below) flow at the same rate. Both circuits have the same current. Remember, the flow rate must be the SAME along the entire tube; likewise, the current is the SAME in the entire series circuit.

6. In a water-siphon system, the analogous rule would be that the overall height between the source water and the dump location, regardless of the path or shape of the hose, is what determines the flow rate. 12. What would be the water analogy to the rule you gave (Q3)? Suppose you wanted to siphon water out of a fish tank quickly: what does the rule tell you? Sample Q3 rule: Brightness of bulbs in a series circuit increases with the number of batteries and decreases with the number of bulbs, and is not dependent on the sequence of the elements. To quickly siphon a fish tank, maximize the height difference between the aquarium water level and the dump sink/bucket.

7. 13. Duke Energy Company serves central North Carolina. It used to be called Duke Power Company. Most likely this name change was made for reasons that have nothing to do with physics, but let’s take them at their word: what were they selling before, and what are they selling now? Is it an energy bill or a power bill that you get at the end of the month? A company selling “power” would be basing your bill on how quickly you use electricity, whereas a company selling “energy” would be basing your bill on how much total electricity you use. In reality, an electrical company is generally only concerned with your total usage, not the rate of your usage, so it is an energy bill you get at the end of each month. POWER vs. ENERGY example: If Person A runs a hair dryer for 5 minutes, and then Person B runs the same hair dryer for 20 minutes, both people used the same amount of power, but Person B used 4 times as much energy. Energy can be measured in killowatt-hours. Power = energy / time Power can be measured in kilowatts. 1 kilowatt = 1000 watts.....so 1 kilowatt-hour is the amount of energy consumed by using 1000 watts for 1 hour.

8. Homework Assignment: 8. Rivers are dammed to make lakes. Sometimes the dam is used to operate a hydroelectric plant, which turns water power into electrical power. Use the internet to find the answers to these questions:  What is the largest hydroelectric plant in the world?  What are the properties of a dam that represent the storage of a lot of energy?  What are the properties that will produce lots of power? Three Gorges Dam in China on the Yangtze River. It can now generate 18,300 megawatts, and will generate 22,500 megawatts when construction is complete. (1 megawatt = 1 million watts) It can generate 80.8 terawatt-hours of electricity per year. (tera- = 1 trillion) A large flood volume (that is, the volume of the reservoir backed up by the dam) represents the “storage” of energy. The Gorges Dam reservoir holds 39.3 billion cubic meters, flooded over 600 square kilometers and required relocation of over 1 million people. Two factors contribute to the power produced: 1) Allowing a large flow rate through the dam will allow production of a large amount of power. A large flow rate powers large turbines that power electrical generators. 2) The difference in height between the water source and outflow generates a greater push on the turbine blades. This is essentially the same as the siphon systems we discussed.....

9. - How to measure voltage and current in an electrical circuit using the appropriate device - The difference between current and voltage in a circuit, and the analogous quantities in a siphon system - The difference between energy and power, and their proper definitions in practical usage WHAT YOU ARE EXPECTED TO KNOW:

10. TODAY’S OUTCOMES: - Review the concepts and definitions of currrent, voltage, power, and energy. ✓ - Investigate the relationship between power, current, and voltage. - Use the data we collected tracking the sun’s shadow to determine how it moves across the sky. ELECTRICITY SUN AND MOON