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BEWARE: Your Attraction To This Unit May Shock You!

Introduction:

Electrons are the particles which are involved in chemical interactions since they located in the outermost parts of the atom. In metals the electrons are loosely associated with all of the atoms in a given sample, allowing the electrons to move easily within a metal. This results in metals being good conductors of energy through the movement of electrons. You will study two forms of energy transfer through electrons: (1) electrostatic charge/discharge and (2) electric current.

Materials:
 
Part 1 Part 2 Part 3 Part 4
Electrostatics Packet sample trays
   foil, salt, tissue, 
     styrofoam
1 inflated balloon
1 electroscope
fabric
Circuit Kit
two D-cells
Edison Program on computer

Preliminary Questions:

1. What will happen if two electrons are brought near each other and released?
2. What does a battery do for an electric circuit?
3. What is Ohm’s Law?
4. How can you charge a balloon?

Procedure:

Part 1 - Each person should complete this part.

1. Read the packet – Electric Charges and Current. It is recommended that you take some notes.
2. Answer completely the question sets I and II from the packet as well as the following questions:
1) What is an electric field? Draw a diagram of lines of force of an electric field.
2) Where is an electric field the strongest? weakest?
3) Upon what does the strength of the electric field depend?
4) What is electricity?
5) How are the processes of conduction and induction different? alike?
6) What is an electroscope? Describe how it works.
7) What is electric discharge? How does it happen.
8) What is grounding?
9) How does a lightning rod work?
3. When your entire group is finished show your work to your teacher and you may check your answers with the key.
 
 
 

Part 2 – Electrostatics – Should be completed as a group.

1. Make one Observations Table to record all observations for the group. You will need to read through the procedure first to determine what needs to be in your table. Have your teacher check your table before going to step #2.
2. Collect necessary materials, except the tape.
3. Briskly rub the balloon with a fabric sample, your clothing, or your hair. Observe how the “rubbed” balloon interacts with one of the sample materials. Record your observations. Touch the balloon to a metal surface.
4. Repeat #3 for all sample materials.
5. What do the interactions of the balloon and the samples tell you about the charging of the balloon? Specifically, do you think the balloon is positive or negative and why?
6. Have your teacher approve your work up to this point.
7. Charge the balloon again. Bring the balloon near the electroscope and record your observations.
8. Sketch the electroscope on your own paper and explain how it works based on your observations.
9. Make sure the electroscope is discharged by touching the top with your finger. How does this discharge the electroscope?
10. Charge the balloon again. Touch and release the top of the electroscope with the balloon and record your observations.
11. Discharge the electroscope.
12. Charge the balloon again. Bring the balloon near the top of the electroscope, without contact, and have your partner touch and release her/his finger to the top of the electroscope while the balloon is near, then remove the balloon and record your observations.
13. What is the charge on the electroscope relative to the balloon at this point?
14. Bring the balloon near the electroscope and record your observations.
15. Have your teacher approve your work up to this point.
16. Now, go get the two pieces of tape. Please get the correct length so as not to waste the tape.
17. Make a handle on each piece of tape by folding about 0.5 cm of one end of the tape over on itself.
18. Stick the first piece of tape to your lab table. Stick the second piece of tape directly on top of the first. Pull, quickly, the bottom piece of tape off the lab table, the top will come with it. Pull, quickly, the two pieces of tape apart and bring the nonsticky sides close to each other. Record your observations.
19. Bring each tape’s nonsticky side near the charged balloon. Record your observations. How is each tape charged relative to the balloon?
20. Stick the two pieces of tape to the lab table next to each other. Pull, quickly, each piece of tape off the lab table and bring the nonsticky sides close to each other. Record your observations.
21. Bring each tape’s nonsticky side near the balloon. Record your observations. How is each tape charged relative to the balloon?
22. Return your lab area to its original pristine condition by cleaning up after yourselves.
23. Have your teacher approve your work up to this point.

Part 3 – Simple Electric circuits – to be completed as a group

1. Arrange one bulb (without a holder), one battery, and one wire in as many ways as you can to make the bulb emit light.
2. Sketch each of your arrangements, including failures as well as successes. Label the sketches of the successes.
a) Describe the similarities among your successful trials.
3. Have your teacher approve your work up to this point.
4. You will now construct a few more circuits. Use the following combinations of batteries and light bulbs and successfully connect them such that the light bulb(s) shine. Be careful when using multiple batteries to always connect (+) to (-). Describe the brightness of the bulb(s) when your circuit is complete. Draw a circuit diagram for each setup.
a) One battery and one bulb
b) One battery and two bulbs
c) Two batteries and one bulb
d) Two batteries and two bulbs
5. Write down what you think: whether the circuits you constructed were series or parallel.
6. Have your teacher approve your work up to this point.
7. Connect the bulbs in holders, one battery, and wires as shown in each circuit diagram of Figure B. Circuits like these are examples of series circuits.
a) Do the bulbs light in each of these series circuits?
8. In the circuit with two bulbs, unscrew one of the bulbs.
a) What happens to the other bulb?
9. Set up the circuit shown in the circuit diagram of Figure C. A circuit like this is called a parallel circuit.
a) Do both bulbs light in this circuit?
10. Unscrew one of the bulbs in the parallel circuit.
a) What happens to the other bulb?
b) In your own words, describe the differences between series and parallel circuits.
11. Try #4 again. Explain any changes.
12. Have your teacher approve your work up to this point.
13. Put a switch in a circuit with two batteries and two bulbs so that it has one bulb always on and the switch toggles the other bulb on/off. Is this circuit series or parallel?
14. Return the circuit kit to its original, pristine condition.
15. Have your teacher approve your work up to this point.


 

Part 4 – Edison: Computer simulated electric circuitry – Individual work until the quiz

1. Click the Edison icon on the computer desktop. Maximize the window after it has loaded.
2. You are to follow a series of tutorials dealing with the basics of electric current, circuits, and Ohm’s Law. Each person should take his/her own notes from each tutorial.
3. Select “Experiments” from the menu bar. Click on each of the following topics. You should answer all of the questions and note all the information provided.
ELECTRICITY
4. Press the switch…What happens? (Observe the green boxes…)
VOLTAGE
5. Do the “Try it”…find the maximum voltage and current that the circuit can handle.
CURRENT
6. What is 1 Ampere defined as?
7. How many electrons equal one coulomb?
DIRECT CURRENT
8. Hook up a voltmeter across one of the bulbs
a. Click on lower right side of screen until you see a voltmeter.
b. Click and drag a voltmeter near a light bulb.
c. Click on one side of the voltmeter and drag a wire to the bulb.
d. Repeat for the other side of the voltmeter.
9. Adjust the slider on the voltage source and note what happens…
OHM’S LAW
10. Try it and summarize the activity
11. Have your teacher approve your work up to this point.
CURRENT CALCULATION (K-U-E-S)
12. Do not press the switch yet
13. Calculate the current for the given circuit, record your answer.
14. Now, press the switch….were you correct?
15. Correct your calculation if you were wrong.
RESISTANCE CALCULATION (K-U-E-S)
16. Try it out by first adjusting the slider on the voltage source.
VOLTAGE CALCULATION (K-U-E-S)
17. Try it out…remember to adjust the slider and notice the results.
18. What is meant by a voltage generator?
RESISTANCE
19. What is a potentiometer?
20. Have your teacher approve your work up to this point.

21. Now on to the “QUIZ”. Write down the formula for Ohm’s law on your paper.
a. If your group has four members each of your should write out (K-U-E-S) for 2 of the first eight so that all eight are done by the group. The manager should do number nine and every member should do number ten.
b. If your group has three members each of you should write out (K-U-E-S) for 3 of the first nine so that the group does all nine. Every member should do (K-U-E-S) number ten.
22. Remember to go back and fix any you get wrong, so that in the end they are all correct.
Record your final score. Your teacher should now be summoned so that you may be given the credit you deserve.