Applied Science - Physics (4B)
Lab 

   
OBJECTIVES:
  • Describing the force produced by a magnet.
  • Investigating why some substances are attracted to magnets.

VOCABULARY:

  • electron
  • magnetic
MATERIALS:

Students experiment with magnetic forces.

BACKGROUND:

Magnetism defies gravity. The stronger the magnet, the less effect gravity has on the object. The stronger the magnet, the more "pull" the magnet has toward objects that are magnetic. This focuses on how the force of magnetism can vary with different objects. Some substances seem not to be affected by magnetism (non-magnetic) whiles others are attracted to it (magnetic). Magnets made out of ALNICO (aluminum, nickel, and cobalt) are much more powerful than steel magnets and are used in almost all loudspeakers manufactured today. Cheap magnets are usually made from iron or an iron alloy and are not permanent. They will lose their magnetism over time.

PROCEDURE:

  1. Review the third grade labs if students find magnetism obscure. This lab will take the students a little further in understanding the force of magnetism. Magnetism is a very complex subject, and very important in our society. New advances such as the MRI (magnetic resonance image) can help locate problems inside the human body without an operation. Magnetism helps store images through magnetic tapes. The uses are endless, and in the future magnetism will probably solve many other problems.
      
  2. There are only three common elements that are naturally magnetic: cobalt, nickel, and iron. Iron is the weakest magnetic element. In 1935, gadolinium was also found to be naturally magnetic. The objective of this lab is for students to explore the mysteries of magnetism by doing several experiments. Use the lab sheet to go over the steps with the students so they can work in groups.
      
  3. Experiment 1. Students should feel the repulsion and attraction of the poles. North/north and south/south repel while north/south attract. The notch on the magnet is North. North is considered the positive side where the magnetism actually begins. South is considered the negative side where the magnetic force reenters the magnet.
      
  4. Experiment 2. Have students put a piece of paper over the magnet. Lightly sprinkle a layer of iron filings over the paper. Have students record the pattern. STRESS that students should not to get iron filings on the magnet. These ALNICO magnets are very strong and it is difficult to clean the magnet. Have students put the filings back in the plastic bag at the end of the experiment.
      
  5. Experiment 3. Have students use the magnet on these items to see if they attract or repel.
      
  6. Experiment 4. Discuss how magnetic forces will go through most substances as long as they are thin enough and the magnet is powerful enough.

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