Analyzing Magnetic Fields with Solenoids 1Running head: ANALYZING MAGNETIC FIELDS WITH SOLENOIDSAnalyzing Magnetic Fields with Solenoids in Introductory PhysicsJames KennicuttPhysics 690Analyzing Magnetic Fields with Solenoids 2AbstractStudent difficulty understanding electricity and magnetism is a common problem in manyphysics courses. Constructing simple solenoids out of a D-Cell battery, copper wire, a nail, and a straw can help students understand this difficult topic. This experiment is designed to help students visualize magnetic fields created by moving electrons in a current carrying wire. Students also learn about the intensity of magnetic fields when an iron core is introduced into the solenoid.Analyzing Magnetic Fields with Solenoids 3Analyzing Magnetic Fields with Solenoids in Introductory PhysicsJames Kennicutt Dept. of Physics, SUNY-Buffalo State College, 1300 Elmwood Ave, Buffalo, NY 14222 <[email protected]>Abstract:Student difficulty understanding electricity and magnetism is a common problem in manyphysics courses. Constructing simple solenoids out of a D-Cell battery, copper wire, a nail, and a straw can help students understand this difficult topic. This experiment is designed to help students visualize magnetic fields created by moving electrons in a current carrying wire. Students also learn about the intensity of magnetic fields when an iron core is introduced into the solenoid.Acknowledgement: This manuscript partially fulfilled requirements for PHY690: Master's Project at SUNY- Buffalo State College, advised by Dr. Dan MacIsaac.Analyzing Magnetic Fields with Solenoids 4 In my experience teaching high school physics, I noticed that students tend to struggle with magnetic fields and the effects of electromagnetism. In order to help students understand this topic, it is important to provide them the opportunity to gain visual and kinesthetic experience with electromagnetism (REF1). Allowing students to construct three-dimensional models of a solenoid (or a wire wrapped in a coil) can be beneficial for helping students with visualizing magnetic fields (REF3) (Picture 01). Theactivity of constructing these models may help students to understand this topic and is also a low cost and simple experiment to conduct. This will also facilitate the exploration of the interactions of solenoids with different materials, the effects of different designs onmagnetism, and the calculation of the magnetic field based on permeability. In order for my students to gain the most knowledge from this activity, I have already covered the basic understanding of magnetic fields surrounding permanent magnets and current-carrying wires (Diagram 02, Diagram 03). For help understanding these concepts, I assign my students an activity using a compass and iron fillings to view various permanent magnet setups. This activity is designed to help students become comfortable using the Right Hand Rule #2 (Diagram 04), predicting the magnetic field around permanent magnets and current carrying wires, and understand basic magnetic fields created by moving electrons. After I have completed these introductions, I feel my students should be prepared to construct a solenoid and predict its magnetic field. One of the most beneficial parts of this activity is that the materials required to complete it are both inexpensive and easily acquired. You will need a length of straw, some magnetic or enamel coated copper wire (about 3 feet per person), an iron nail (about 9 cm long), D-Cell battery, compass, and a few paper clips (Picture 01). TheseAnalyzing Magnetic Fields with Solenoids 5materials can be purchased at a variety of stores on the Internet or locally, and cost me around $10.00 for a class of 25 students. Many of these materials are able to be recycled for future classes as well.Another benefit to the activity of constructing solenoids is that the procedure is quite straightforward. To begin the experiment, I make sure that both ends of the copper wire are stripped then I ask my students to wrap the wire around the straw with the nail placed inside for support. I always ask my students to note the number of times they wrapthe wire around the straw for later calculations. The wire should not be wrapped too tightly around the straw because you want the students to be able to insert and remove theiron nail so that the solenoid can have either an open-core (no nail)(Picture 03) or an iron-core (nail inside)(Picture 04). There should be a few inches of unwrapped wire at both ends of the solenoid so that there is enough room to press the stripped sections of wire to the battery terminals. Now that the solenoid is complete I have my students connect the two ends to a D-Cell battery to the stripped sections of wire to send a current through the wire and create a magnetic field around the solenoid (Diagram 01). In this experiment, it is important to note that the D-Cell battery will in essence be shorted causing the wire to become warm. It is advantageous to allow the battery to rest every 30 seconds to allow the cell to cool down and to ensure you do not to burn yourself on the warm wires. In order to learn about different designs of solenoids and gain a better idea of the magnetic fields they create, students should be allowed to construct their own solenoids. Throughout the activity with my students, I instruct them to try a variety of different designs of solenoids in order to compare the different effects with their partners. ForAnalyzing Magnetic Fields with Solenoids 6example, before the activity, I cut the straws into different lengths so students can compare the magnitude of the magnetic field of their solenoids (Picture 02). I also ask my students to note the number of loops they wrap the wire around the straw in order to discuss the influence of the number of loops on the magnetic field. Other extensions to this activity include ways for students to explore different designs for their solenoids and the effects these designs create. Many alterations to students’ solenoid designs can help them observe the ways in which these changes can affect the magnetic field. Even alterations as simple as wrapping a different number of loops around their straws, can produce interesting results that the students can then compare to their partner’s solenoid. My students generally find that some solenoid designs create a larger magnetic field than other designs. For instance, one of my groups
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