Question

Testing Electromagnets



Students conduct two investigations using paper clips to observe the magnetic field produced by an electromagnet. The strength of the magnetic field is measured by the number of paper clips picked up by the electromagnet. The model shows the general setup for the electromagnet used in each investigation.



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In the first investigation, the students vary the number of coils wrapped around the steel nail. The data table shows the number of paper clips picked up by the electromagnet.


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In the second investigation, the students use the same number of coils around the nail but change the type of nail. They record the properties of each nail and the number of paper clips that the electromagnet picked up.


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The students want to perform the same procedure with a brass nail. The properties of brass are listed in the table.



Metal Level of Electrical Conductivity Magnetic (Yes/No)
Brass Very high conductivity No


Which best describes what the students will observe?


The brass nail will pick up the same number of paper clips as aluminum because brass is not magnetic.


The brass nail will pick up more paper clips than iron because brass has the highest electrical conductivity.


The brass nail will pick up more paper clips than steel but less than iron because brass has a high electrical conductivity but is not magnetic.


The brass nail will pick up more paper clips than aluminum but less than steel because brass has a low electrical conductivity but is magnetic.

Answer 1

The brass nail will pick up the same number of paper clips as aluminum because brass is not magnetic.

Reason: An electromagnet’s strength depends on having a ferromagnetic core (high magnetic permeability) to concentrate the field. Electrical conductivity doesn’t make a material magnetic, so a non‑magnetic brass core will behave like a non‑magnetic aluminum core.