In 1881, President James Garfield was shot and the lead bullet was in an unknown location. The American inventor Alexander Graham Bell was called upon to create a device that could pinpoint the location of the bullet without causing further harm to the president. In the course of approximately two months, Bell had managed to utilize inductors in a balanced configuration to detect metal. The coils were connected with a telephone speaker.  A piece of metal close to the coil would disturb the balance and a sound would emit from the telephone. Since the range of the detector was known, the bullet’s position could theoretically be pinpointed. Unfortunately for President Garfield, his mattress was a new and unconsidered invention: the spring mattress. Although the president’s bullet could not be found, the invention was later proven effective on American soldiers. Thus, the metal detector is the first known attempt at successful medical imaging.

Here is a picture of Bell using his invention to attempt to find the bullet in President Garfield.

Prior to my arrival, a cost effective replica of Bell’s metal detector had been, for the most part, constructed. One aim of this project is to make the equipment needed for the tutorial easily accessible and inexpensive to any instructor. We have experimented using store bought coils and coils we wound ourselves using wire from a jewelry making kit. Both set ups proved effective. To further make the metal detector cost effective, we found a computer oscilloscope program which makes small changes in the induction bridge visible.

My research project was mainly to create a tutorial so students can comprehend how our metal detector set up works. I started by doing a literature search. I found articles that had done studies testing students understanding of electricity and magnetism. I tried to address what other people have found as comprehension issues for electricity and magnetism and incorporate teaching techniques that have been found most effective. A summary of the findings are stated below:

1. 1.Students attribute real existence to magnetic field lines (Guisasola)
   

2. 2.The electric charge, whether moving or at rest is identified as the source of the magnetic field. Students have issues identifying the source of a magnetic field (Guisasola)
   

3. 3.Magnets are seen as charged bodies (Guisasola)
   

4. 4.There is much confusion between electricity and magnetism (Guisasola)
   

5. 5.Students think that the induced currents varies proportionally with the current in the solenoid instead of with the change of current (Tong, Gunstone).
   

6. 6.Students think there must be contact between magnetic flux field lines and eternal coil in order for an emf to be induced in the coil (Tong, Gunstone).
   

7. 7.An emf is is thought to be induced in a coil moving through a uniform magnetic field as opposed to only when the coil is entering or leaving a uniform field (Saglam, Miller)
   

Other studies researched how students responded to new ways of instruction. Although researchers went about it in numerous ways, the data is consistent across papers that active learning, or active participation, is more effective then the traditional lecture setting. Unfortunately interactive learning takes substantially more time and monetary resources. The metal detector tutorial aims to further encourage active learning without the monetary disadvantage.

Upon identifying widespread misconception students have while learning electromagnetism, I designed activities for my tutorial that addresses and attempts to clarify these misconceptions.