Lesson 3 - Magnetic Force
- Goal 1: Students will determine the strength of the magnetic field if given the force on a charge in a magnetic field.
- Goal 2: Students will determine the magnitude & direction of the force on a wire carrying current in a magnetic field.
- Goal 3: Students will use the right hand rule to determine the direction of the force on a charge moving through a magnetic field.
Essential Question - How are the physics ideas of force and magnetism connected?
First 0-10 minutes of class: Class with being with a question and a demonstration. Students will be asked what happens to a television screen when a magnet is brought near the screen. Discuss why. Proceed with the following demonstration: Lay a horseshoe magnet on is side so that one pole is above the other. Connect a wire to a power supply and support the wire so that is passes through the center of the poles of the horseshoe magnet. (Use a ring stand and supports). Remind students that current is made up of moving charges and that they will observe the magnetic field exerting a force on the charges. Turn on the power supply, and gradually increase the current in the wire until the wire is forced to one side or the other. Ask students what will happen if the direction of the current is reversed. Turn off the power supply, detach the wires, and attach them to the opposite terminals. Turn on the power supply, and increase the current to confirm the students' hypothesis. Have student sketch the magnetic fields of the magnet and the wire. (Demonstration adapted from Holt Physics text).
30 minutes of class: Direct instruction and group problem solving. The teacher will go through how to calculate the strength of the magnetic force on a particle moving perpendicular to the field using the following expression:
B = Fmagnetic/qv
magnetic field = (magnetic force on a charged particle)/(magnitude of charge)(speed of charge)
30 minutes of class: Direct instruction and group problem solving. The teacher will go through how to calculate the strength of the magnetic force on a particle moving perpendicular to the field using the following expression:
B = Fmagnetic/qv
magnetic field = (magnetic force on a charged particle)/(magnitude of charge)(speed of charge)
Next Students will learn to use the right hand rule to find the direction of the magnetic force. Using the expressions and the right hand rule, student will solve three practice problems in their notebooks. The practice problems can be found on page 775 of their text. They can work together, and we will discuss the answers as a class.
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The final portion of direct instruction will involve learning how to use the following expression related to the force on a current-carrying conductor perpendicular to a magnetic field.
Fmagnetic = BIl
magnitude of magnetic force = (magnitude of magnetic field)(current)(length of conductor within B)
Student will complete a few practice problems related to these concepts as we work through the class power point that comes with the Holt curriculum. The power point provided guided practice as we work together as well as a couple of virtual demonstrations. It should take about 15 minutes to complete.
Final 40 minutes of class:
Students will have the remainder of class time to work together on the following two tasks. They will work in groups of three. All work for these tasks should be organized into an easy to understand format of their choice (spreadsheet, word processing document, power point, etc...) and posted to our class blog. Work must be upload by the end of the week. Students will then have the weekend to each review the class blog and post at least one meaningful comment (as defined by class expectations) and at least one meaningful response to a classmate's comment.
Task 1: Magnetic force was first described by the ancient Greeks, who mined a magnetic mineral called magnetite. Magnetite was used in early experiments on magnetic force. Research the historical development of the concept of magnetic force.
Group 1 - describe the work of Peregrinus.
Group2 - describe the work of William Gilbert.
Group 3 - Describe the work of Oersted and Faraday.
Your group's findings related to your scientist can be presented in whatever format you choose. You can use a video, a cartoon strip, a document, a power point, a podcast, a concept map... the possibilities are endless. Make sure it can be uploaded to our class website to be viewed by your classmates.
Task 2: Imagine you have been hired by a manufacturer interested in making kitchen magnets. The manufacturer wants you to determine how to combine several magnets to get a very strong magnet. He also wants to know what protective material to use to cover the magnets. Develop a method for measuring the strength of different magnets by recording the maximum number of paper clips they can hold under various conditions. First open a paper clip to use as a hook. Test the strength of different magnets and combinations of magnets by holding up the magnet, placing the open clip on the magnet, and hooking the rest of the paper clips so that they hang below the magnet Examine the effect of layering different materials between the magnet and the clips. organize your data in tables and graphs to present your conclusions. Post your findings on our class website.
Fmagnetic = BIl
magnitude of magnetic force = (magnitude of magnetic field)(current)(length of conductor within B)
Student will complete a few practice problems related to these concepts as we work through the class power point that comes with the Holt curriculum. The power point provided guided practice as we work together as well as a couple of virtual demonstrations. It should take about 15 minutes to complete.
Final 40 minutes of class:
Students will have the remainder of class time to work together on the following two tasks. They will work in groups of three. All work for these tasks should be organized into an easy to understand format of their choice (spreadsheet, word processing document, power point, etc...) and posted to our class blog. Work must be upload by the end of the week. Students will then have the weekend to each review the class blog and post at least one meaningful comment (as defined by class expectations) and at least one meaningful response to a classmate's comment.
Task 1: Magnetic force was first described by the ancient Greeks, who mined a magnetic mineral called magnetite. Magnetite was used in early experiments on magnetic force. Research the historical development of the concept of magnetic force.
Group 1 - describe the work of Peregrinus.
Group2 - describe the work of William Gilbert.
Group 3 - Describe the work of Oersted and Faraday.
Your group's findings related to your scientist can be presented in whatever format you choose. You can use a video, a cartoon strip, a document, a power point, a podcast, a concept map... the possibilities are endless. Make sure it can be uploaded to our class website to be viewed by your classmates.
Task 2: Imagine you have been hired by a manufacturer interested in making kitchen magnets. The manufacturer wants you to determine how to combine several magnets to get a very strong magnet. He also wants to know what protective material to use to cover the magnets. Develop a method for measuring the strength of different magnets by recording the maximum number of paper clips they can hold under various conditions. First open a paper clip to use as a hook. Test the strength of different magnets and combinations of magnets by holding up the magnet, placing the open clip on the magnet, and hooking the rest of the paper clips so that they hang below the magnet Examine the effect of layering different materials between the magnet and the clips. organize your data in tables and graphs to present your conclusions. Post your findings on our class website.