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ANALYZE IT

Instruct students to complete the Analysis Questions in their SDRs then discuss them as a class. Use the suggested responses below to guide students’ answers.

Analysis Questions After Trial 3:

1. Question: What effect did increasing the number of batteries have on the current flowing through the circuit? Current increased from 1.88 A to 2.24 A as the number of batteries increased.

2. Question: Did changing the number of batteries affect the strength of the electromagnet? Support your answer with data from the experiment. Increasing the number of batteries increased the magnetic strength of the magnet by causing it to attract more paper clips. Increasing the batteries from one to two increased the number of paper clips attracted by the magnet from one to three. Increasing the number of batteries to three made the magnet strong enough to pick up five paper clips.

3. Question: How are the current and the strength of the electromagnet related? Support your answer with data from the experiment. The increasing current caused the magnet to attract more paper clips. This suggests that there is a pattern between the current and the strength of the magnet because increasing the batteries from 1 to 3 resulted in an increase in current from 1.88 A to 2.24 A and an increase in the number of paper clips attracted from 1 to 5.

 

 

4. Question: How many turns of wire were on the electromagnet?  20

5. Question: Measure the length of the coil in centimeters. What is the length of the coil? 3 cm

6. Question: What is the length of the coil in meters? Remember 100 cm = 1 meter. 0.03 meters

7. Calculate the value for “n” which is the ratio of the number of turns of wire (N) to the length of the coil (L) in meters. Use the following formula to calculate “n” in turns per meter.

 n = N/L

 n = 20 turns / .03 meters and n = 667 turns per meter

  

8. Record: Write the values for n for each Trial in Table A.

 

9. Calculate the magnetic field for each electromagnet using the values for current (I), “n” and the constant μ0. Use the formula below for help. Record: Write the value for the magnetic field of each electromagnet in Table A.

B = magnetic field

μ0 = 12.57 × 10-7 Tesla-meters/amps.

n = N/L (N = number of turns of wire, L = length of the coil) I = current in amps

B = μ0nI

B= (12.57 × 10-7 Tesla-meters/amps) × (n) × I.

 

10. Question: Look at the formula for magnetic field. Is there a relationship between current (I) and the strength of the magnetic field (B)? Use the formula below and the explanation in the previous Background for help.

 B = μ0 × n × I

Based on the formula, there is a relationship between current and the strength of the magnetic field.

 

11. Question: Why did changing the number of batteries affect the magnetic field of the electromagnet? Explain your answer using the formula for magnetic field again.

B = μ0 × n × I

The formula for B shows that the current is directly related to the strength of the magnetic field. Increasing the number of batteries caused the current to increase. Therefore, increasing the number of batteries increased the strength of the magnetic field by increasing the

 

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Analysis Questions After Trial 6:

1. Question: Calculate the value for “n” for the electromagnet with 15 turns of wire. Use the following formula to calculate turns per meter:

n = N/L

n = 15 turns /.03 meters and n = 500 turns per meter  

2. Question: Calculate the value for “n” for the electromagnet with 20 turns of wire. Use the following formula to calculate turns per meter:

n = N/L

n = 20 turns /.03 meters and n = 667 turns per meter  

3. Question: Calculate the value for “n” for the electromagnet with 25 turns of wire. Use the following formula to calculate turns per meter:

n = N/L

n = 25 turns /.03 meters and n = 833 turns per meter 

4. Record the values for “n” in Table B.

5. Question: Calculate the magnetic field for each electromagnet using the numbers for current, “n”, and the constant μ₀. Use the formula below for help.

B = magnetic field

μ0 = 12.57 × 10^-7 Tesla-meters/amps.

n = N/L (N = number of turns of wire, L = length of coil in meters) I = current in amps

B = μ0nI

B= (12.57 × 10^-7 Tesla-meters/amps) x (n) x I.

 

6. Record: Write the value for the magnetic field of each electromagnet in Table B.

7. Question: How did changing the number of coils affect the number of paper clips the electromagnet could hold? Increasing the number of coils from 15 to 25 increased the number of paper clips that the electromagnet could hold from 4 to 9. 

8. Question: How did changing the number of coils affect the magnetic field? Increasing the number of coils increased the magnetic field. 

9. Question: Look at the data. Did changing the number of turns of wire change the current in the electromagnet? Increasing the number of turns of wire did not change the current.

 

10. Draw a best fit line graph to show the relationship between current and magnetic field. Use data from Table A to create the graph. Refer to the Procedures Determination and Graphing of Independent and Dependent Variables and Drawing of a Best Fit Line for assistance if necessary.

 

11. Draw a best fit line graph to show the relationship between the number of coils and the magnetic field. Use data from Table B to create the graph. Refer to the procedures for Determination and Graphing of Independent and Dependent Variables and Drawing of a Best Fit Line for assistance if necessary.

 

 

12. Question: Study the two graphs in problems 10 and 11. What conclusions can you make about current, the number of coils, and the strength of a magnetic field? How does this relate to the formula for a magnetic field? Both the number of coils and the amount of current are directly related to magnetic field and are included in the formula for magnetic field. As the number of coils increases, the magnetic field increases. As the current increases, the magnetic field increases. Likewise as both the number of coils or current decreases, the magnetic field decreases.

GET FOCUSED

What is the relationship between electricity and magnetism? 

There is a direct relationship between electricity and magnetism. The flow of current through a wire generates a magnetic field perpendicular to the wire. As the amount of current flowing through the wire increases, the magnitude of the magnetic field increases. As current increased from 1.88 A to 2.24 A, the magnitude of the magnetic field increased from 15762 × 10-7 T to 18781 × 10-7 T, allowing the number of paper clips attracted to the magnet to increase from 1 to 4.

 

What factors affect the strength of an electromagnet?

The strength of an electromagnet is affected by the number of turns of wire in the coil over a specific length.  The strength of an electromagnet is also affected by the amount of current flowing through the wire.  As the number of turns of wire in the coil increases, the strength of the electromagnet increases. Decreasing the number of turns of wire decreases the strength of the electromagnet. Increasing the current also increases the strength of the electromagnet. Decreasing the amount of current decreases the strength of the electromagnet.