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# Investigating electricity part 2

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DSVS, 8th Grade, Lab 3

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### Investigating electricity part 2

1. 1. Investigating Electricity Part 2<br />DSVS Spring 2011<br />Eighth Grade<br />Lab 3<br />
2. 2. Lab Set Up<br />These labs primarily consist of measuring current in different portions of circuits using an ammeter. <br />If you’re short on time, I’d suggest skipping either 6 or 7 (but not both).<br />If you find the photos confusing, there are circuit diagrams in the student handouts.<br />The circuits suggested require more wires than the kit provides. You can solve this by removing a battery in most cases.<br />Part 10 is the most fun. Make an effort to get to this lab, even if you just demonstrate if for them. <br />
3. 3. 6: Measuring the Current in a Series Circuit<br />Have the students connect the circuit shown. <br />They will then connect the ammeter at different locations and record their observations. <br />
4. 4. 7: Measuring the Current in a Parallel Circuit<br />Have the students connect the circuit shown. <br />They will then connect the ammeter at different locations and record their observations. <br />
5. 5. 8: The Effect of Resistance in a Circuit<br />Explain to the students that bulbs act as resistance to the current<br />Connect the circuits shown.<br />What is the relationship between resistance and current?<br />
6. 6. 9: Variable Resistance in a Circuit<br />First you have to make the variable resistor.<br />Coil wire around another object like a pencil or a nail<br />
7. 7. 9: Variable Resistance in a Circuit<br />Connect the circuit as shown. <br />The bulbs will probably not light.<br />
8. 8. 9: Variable Resistance in a Circuit<br />Vary the resistance by changing the connection point to the resistor. <br />At this point the bulbs should light.<br />Q: What happens to the current in the circuit when you move the lead back and forth?<br />A: The current varies between its max and min.<br />
9. 9. 10: How a Fuse Works<br />Connect the circuit shown.<br />Connect a wire across the bulb.<br />Q: What happens when a short circuit is made?<br />A: The bulb goes out.<br />The connection is made with a few twisted stands of steel wool.<br />The steel wool has to be very thin for this to work.<br />
10. 10. 10: How a Fuse Works<br />Modify the circuit by completing the connection with a few twisted strands of steel wool. <br />The steel wool has to be very thin for this to work<br />The steel wool acts as a fuse.<br />
11. 11. 10: How a Fuse Works<br />Short out the circuit again.<br />The steel wool will burn up. <br />Instruct students to be careful and supervise well during this part of the lab.<br />You may also wish to just demonstrate.<br />Q: Why does the fuse melt?<br />A: The fuse melts because the current is large and there is almost no resistance in the circuit. The fuse becomes hot and melts.<br />Q: Why do you need a fuse in a circuit?<br />A: The fuse protects the circuit. If the fuse did not melt, a short circuit could cause the wires in the circuit itself to melt and possibly start a fire. <br />
12. 12. 10: How a Fuse Works<br />
13. 13. Wrapping it Up<br />Clean up.<br />Answer student questions<br />Conclude the lab, discussing the experiments performed.<br />Say goodbye to the students, tell them how much you enjoyed working with them.<br />
14. 14. References<br />These activities and discussion questions are from:<br />“Investigating Electricity”<br />Hubbard Scientific Inc. Chippewa Falls, Wisconsin<br />Training slides and photos<br />Lerin Rutherford<br />