Contextualization

Physics is a discipline that, among other things, concerns itself with describing and understanding the natural phenomena that occur around us. One of these phenomena is the magnetic field, an essential aspect of our existence whose most visible effects are observed in magnets and compasses, but which also has a wide range of applications in many other domains.

The magnetic field is a vector quantity, which means it has both magnitude and direction. It is generated by electric currents or moving electric charges and is described by field lines. These lines come out of the north pole and enter the south pole, forming a kind of 'loop'.

The solenoid is a device commonly used to produce a uniform magnetic field. It consists of a coil of conducting wire wound in a helical shape. When an electric current passes through the solenoid, a magnetic field is created inside it.

Understanding the principles of operation of solenoids and the magnetic field they generate has a profound impact on many areas of science and technology. For example, solenoids are fundamental in the operation of electric motors, generators, and transformers - machines that are at the foundation of our industrial civilization. They also play a key role in magnetic resonance imaging, a medical technique that allows visualization of the interior of the human body without the need for surgery.

Furthermore, we can also find the concept of a magnetic field generated by a solenoid in the study of astrophysical phenomena, such as star formation and the magnetic activity of stars.

For your research, you can use the book 'Physics for Scientists and Engineers' by Paul A. Tipler and Gene Mosca, and the website 'Physics Classroom' which contains various content on the subject. Additionally, you can watch the video 'Magnetic field of a solenoid - Physics - #Lesson 09' on the channel 'Physics EAD - Prof. Sérgio Pereira' on YouTube, it is a great tool to learn more about the topic.

Practical Activity

Activity Title:

Building and analyzing a solenoid: Exploring the magnetic field.

Project Objective:

To understand how the electric current through a solenoid generates a magnetic field and study the properties of this field. Additionally, one should understand the importance and application of solenoids in everyday life.

Detailed Project Description:

In this activity, students will build a simple solenoid and establish the connection between the electric current passing through it and the generated magnetic field. Students should observe the various properties of the magnetic field, such as direction and strength, and manipulate them by modifying the number of turns of the solenoid, the current passing through the wires, and the core material. Students will be encouraged to make predictions based on the theory studied and test them through experiments.

The activity will last for two weeks, with groups of 3 to 5 students working together.

Required Materials:

• Copper wires
• Battery
• Aluminum foil
• Iron filings
• Sheet of paper
• Iron core (a large nail, for example)
• Multimeter
• Scissors

Detailed Step-by-Step for Activity Execution:

1. Wind the copper wire around the iron core to form the solenoid. The number of turns should be recorded.

2. Connect one end of the solenoid to the battery and the other end to the multimeter to measure the current passing through the solenoid.

3. Place a sheet of paper over the solenoid and spread iron filings on it.

4. Pass the current through the solenoid and observe the pattern formed by the iron filings. This pattern represents the generated magnetic field.

5. Repeat steps 3 and 4 by modifying the number of turns of the solenoid and the current passing through it. Record all modifications and their respective observations.

6. Summarize your observations and analyze the results in light of the theory studied.

Project Deliverables:

After completing the practical part, the groups should deliver:

1. A written report detailing the experience. The report should be at least 5 pages long and should contain the following topics:

   • Introduction: Describe what a solenoid is and why it is important. Briefly explain the purpose of the experiment and what you expect to learn from it.
   • Development: Discuss the theory behind solenoids and magnetic fields and describe the experiment step by step, including what was done, how it was done, and what materials were used. Present the observations made and the data collected.
   • Results and Discussion: Present all the results obtained and discuss them in light of the theory studied. Compare your results with your initial predictions and explain any discrepancies.
   • Conclusion: Summarize what was learned during the experiment, the difficulties encountered, and how they were overcome. Discuss what the results mean and how they relate to the theory studied.
   • Bibliography: List all sources used during the preparation and execution of the experiment.

2. Oral Presentation: Each group should give a 10-minute oral presentation to the class, explaining the project and sharing the results. The presentation should include a discussion of the skills acquired during the project execution, including technical skills (e.g., magnetic field calculations) and socio-emotional skills (e.g., teamwork, time management).

3. Solenoid Prototype: The physical delivery of the solenoid built by the group.