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Electricity and Magnetism

Investigation 3 – Lab

 

 

 

 

 

 

 

MINDSET

This Investigation is designed to:

  • demonstrate to you that a nonmagnetic iron electrode can become a temporary magnet when wrapped in a coil of wire to which a current is applied.
  • demonstrate to you that the magnetic field of an electromagnet is directly affected by the amount of current which passes through its coil.
  • demonstrate to you that the magnetic field of an electromagnet is directly affected by the number of coils of wire around the magnet.

BE PREPARED

Teacher Preparation for the Investigation includes the following. This preparation should be done prior to students arriving in the lab. 

1. Cut five (5) 50 cm pieces of wire with the wire cutters. Use the wire cutters

to strip approximately 8 mm of insulation from the ends of each piece of wire.

2. Cut five (5) 5 cm pieces of tape.

3. Place all materials at a central distribution center.

4. Divide the class into five cooperative groups.

Student Preparation for the Investigation includes having students gather the following materials. This preparation takes place on lab day after student lab groups have settled at their assigned lab tables. 

Note: The materials are listed in students’ SDRs. They are also listed below for your reference.

  • 1 multimeter 
  • 2 alligator test leads 
  • 1 50 cm piece of wire 
  • 4 D cell batteries 
  • 4 battery joiners 
  • 1 nail 
  • 15 paper clips 
  • 1 metric ruler 
  • 1 roll of masking tape 

Direct one student from each lab group to collect the materials listed in their SDRs. 

 

INVESTIGATE

  • Inform students that during this Investigation, they will continue their examination of current by studying how current influences the magnetic field of an electromagnet.
  • Encourage students to reflect on the PreLab video as they move through the procedural steps.
  • Explain to students that during the Experiment, every procedural step is important. If one step is skipped, data can become invalid. To help students keep on track, direct them to read each step thoroughly, complete the step, then check it off (Read it – Do it – Check it off).
  • Direct students to complete the procedural steps in their SDRs.

Note: The procedural steps are listed below for your reference. Teacher “Notes” are inserted, as needed, to help facilitate the lab.

Note: Most of the illustrations in the lab protocol can be enlarged for detail by clicking on the image.

  1. Place the batteries in the battery joiners. Make sure that the positive terminal of the battery is turned to the positive end of the battery joiner.
  2. Assemble the circuit using the diagram, the instructions, and the individual pictures. Use the Multimeter Use and Operation procedure for assistance if necessary. 

a. Place the connector of a red probe into the “10ADC” outlet on the front of one multimeter.

b. Place the connector of a black lead into the “COM” outlet of the multimeter.

c. Turn the selector on one multimeter to the “10A” mark. 

 

3. Assemble the electromagnet as follows:

a. Measure 2 cm from the point of the nail and make a mark.

b. Measure 3 cm from the first mark (5 cm from the point) and make a second mark. 

c. Wrap the wire around the nail between the two marks, creating a coil with 20 turns around the nail in a single layer.

d. Be sure that the loops are pushed tightly together.

5. Connect two alligator test leads, one to each terminal of the battery joiner.

6. Connect the electromagnet to the battery by connecting one end of the wire around the electromagnet to the alligator test lead attached to the positive terminal of the battery joiner.

 

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Trial 1:

  1. In Trials 1, 2, and 3, you will investigate the effect of current on the magnetic field of an electromagnet. Trial 1 uses one battery.
  2. Determine the current as follows:

a. Place the tip of the red probe of the multimeter in the free loop of the electromagnet wire.

b. Place the tip of the black probe on the alligator test lead of the negative wire from the battery joiner.

c. Record the current displayed on the multimeter in Table A of the Student Data Record.

d. Disconnect the multimeter from the circuit.

3. Determine how many paper clips the magnet can pick up:

a. Connect the free end of the electromagnet wire to the alligator test lead attached to the negative terminal of the battery joiner.

b. Hold a paper clip up to the electromagnet near the wire coil.

c. If the paper clip is attracted to the electromagnet, try a second paper clip.

d. Continue attempting to add paper clips until the magnet will no longer hold additional paper clips.

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Trial 2:

1. Add a second battery to the electromagnet:

a. Disconnect the alligator test lead from the negative terminal of the battery. 

b. Connect the positive terminal of a second battery to the negative terminal of the first battery by snapping or placing the two battery joiners together.

c. Attach the free alligator test lead to the negative terminal of the second battery.

2. Assemble the multimeter and measure the current generated in the circuit by the two batteries. Refer to the Procedure, Multimeter Use, and Operation if necessary.

3. Record the current in Table A.

4. Determine how many paper clips the magnet can pick up with two batteries. Record the number of paper clips in Table A.

 

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Trial 3:

  1. Add a third battery to the circuit.

a. Unsnap the first two batteries.

b. Place the third battery between the first two. 

c. Connect the batteries together at their terminals by snapping or placing the battery joiners together. 

2. Assemble the multimeter and measure the current generated in the circuit by the three batteries. Refer to the Procedure, Multimeter Use, and Operation if necessary.

3. Record the current in Table A.

4. Determine how many paper clips the magnet can pick up with three batteries. Record the number of paper clips in Table A.

5. Disconnect the free end of the electromagnet from the wire attached to the negative terminal of the battery joiner. Do not unsnap the batteries.

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Trial 4:

  1. In Trials 4, 5, and 6 you will investigate the effect of adding more turns to the electromagnet on the magnetic field.

2. Set up the electromagnet according to the following instructions:

a. Add a fourth battery to the three batteries from the last Trial.

b. Carefully unwrap 5 turns of wire from the nail so that there are 15 turns of wire. Spread the coil of wire to evenly cover the distance between the two marks on the nail.

c. Clip two alligator test leads, one to each free terminal of the batteries.

d. Connect the alligator test lead from the positive terminal to one end of the coil on the electromagnet.

3. Add the multimeter to the circuit to determine the current. Refer to the Procedure, Multimeter Use, and Operation if necessary. Measure the current and record it in Table B.

4. Disconnect the multimeter from the circuit.

5. Connect the free end of the electromagnet wire to the alligator test lead from the negative terminal of the batteries.

6. Record the number of paper clips the electromagnet can hold in Table B.

7. Disconnect the electromagnet wire from the negative terminal alligator test lead.

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Trial 5:

1. Add five additional turns of wire to the electromagnet so that there are 20 turns of wire. Make sure that the coil of wire covers the distance between the two marks on the nail.

2. Add the multimeter to the circuit to determine the current. Refer to the Procedure, Multimeter Use, and Operation if necessary. Measure the current and record it in Table B.

3. Connect the free end of the electromagnet wire to the alligator test lead from the negative terminal of the batteries.

4. Record the number of paper clips the electromagnet can hold in Table B.

5. Disconnect the electromagnet wire from the negative terminal alligator test lead.

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Trial 6:

  1. Add five additional turns of wire to the electromagnet so that there are 25 turns of wire. Spread the coil of wire to evenly cover the distance between the two marks on the nail.

 

2. Add the multimeter to the circuit to determine the current. Refer to the Procedure, Multimeter Use, and Operation if necessary. Measure the current and record it in Table B.

3. Connect the free end of the electromagnet wire to the alligator test lead from the negative terminal of the batteries.

4. Record the number of paper clips the electromagnet can hold in Table B.

5. Disconnect the electromagnet wire from batteries. Do not unsnap the batteries as they may be warm.

CLEAN UP

Be sure to clean up your lab bench after completing your experiments.