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Electromagnetic Induction -
Oersted Effect
|
| Subject Area |
Electromagnetism |
| Age or Grade |
9-10 |
| Estimated
Length |
60 minutes |
| Prerequisite
knowledge/skills |
fundamentals of electric circuits, basic knowledge about magnetism |
| Description
of New Content |
Oersted Effect, magnetic fields of current carrying wires |
| Goals |
The students use compasses to detect the magnetic fields of a current carrying wire. It is not the wire which is magnetized but the magnetic field is created by the moving charges in the wire. |
| Materials
Needed |
equipment to build a simple electric circuit (wires, batteries, light bulbs), compasses, equipment to visualize the magnetic field of the wire (e.g. iron filings on a plexiglass plate which holds a current carrying wire), electromagnet |
|
Procedure
|
Opener The students had heard before about a connection between electricity and magnetism. Ask them to answer them how this connection might look like. Review some basics about magnetic fields. Use of compasses as detectors of magnetic fields Development 1. students should realize that an neutral, unmagnetized metal or insulator doesn't have a magnetic field 2. What about static charges. Create static charges (e.g. with scotch tape). The electrostatic force between 2 tapes can easily be seen, but compasses do not react. So no magnetic field is produced whatsoever 3. let them set up a simple electric circuit (like they have done before in class). An indicator that a current is flowing could be a light bulb in the circuit. Put the compass on the wire that the needle is aligned parralel (since the field lines once the current is turned are circular around the wire.) Once the current is turned on the magnet needle will be deflected. 4. Demonstrate the students an electromagnet. Discuss how it works. Alternatively one cold take some time to let the students build their own electromagnets (using mails and magnet wire) 5. The central result is that moving electric charges (electric currents) produce a magnetic field 6. If available one could use a setup to visualize the field lines. We used a plexiglass plate which had wires running through it. The magnetic field lines were readily visible using iron filings
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| References | We used the follwoing handout for the class |