Lesson Plan on Magnetic Fields

Objectives: Students will be able to

  1. replicate a dipole field line using a bar magnet.
  2. explain how the Earth acts like a magnet.

Grade Levels: 8-12

Background Information:

Magnetism of an iron magnet is caused by electric currents associated with the spinning motion of atomic electrons. To get a general picture of a magnetic field, think of iron filings sprinkled around a bar magnet. The iron filings would take on the appearance of the characteristic dipole pattern.

[Creation of Earth's magnetic field]
The Earth's magnetic field is generated in the mobile outer core composed of liquid iron and nickel. The source of the magnetic field cannot be permanently magnetized material, because the interior of the Earth is too hot for any material to retain its magnetism. This means that the Earth's magnetism must be generated dynamically by swirling circulation in the liquid metal. This causes the Earth to behave much like a giant bar magnet. Think of the Earth as having a giant bar magnet passing from one pole to the other pole through its center.

[Earth's Magnetic Field]
In NASA's Near Earth Asteroid Rendezvous mission, the spacecraft will carry a magnetometer that will measure the strength of Eros' magnetic field. The major purpose of determining the strength of Eros' magnetic field is to help indicate its origin. If a strong magnetic field is detected at Eros, this may indicate that Eros is a piece of a larger body that, like earth, once generated its own magnetic field. Presence of a magnetic field in conjunction with data collected from other instruments, such as the Near Infrared Spectrometer and the Multispectral Imager, can further indicate the composition of Eros.

Activities

Activity: Producing a Dipole Field Line

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[LMGFP home page] Contact Karen Krupinsky (kgurley@gsfc.nasa.gov) or
Tammy Seergae (tseergae@umd.edu) for further information.