The purpose of the current loop simulation is to let the user explore the magnetic fields surrounding one or two current loops. A complete worksheet is available to guide students in this exploration. Note the following:
- The number of B-lines is proportional to the current in the loops (I amps).
- The B-field strength is proportional to the spatial density of the B-lines: that is, a lot of lines close together means a strong B-field
- B-lines are complete: that is, they close on themselves and do not terminate on any “magnetic charges”. “Magnetic charges” do not exist.
- The B-field is stronger near a wire carrying current.
Student Worksheet Downloadable Word Doc
We used the following word document as a lab procedure in the PHY112 class. However, it can be used with more advanced or engineering-level classes, because the concepts are significant.
Points for Discussion
- The magnetic field is a force field: The force on a current is perpendicular both to current vector and the B-field line. The magnitude of force is proportional to the current acted upon and to the spatial density of the B-field lines.
- All magnetic field lines are complete loops. They appear to terminate on the poles of a permanent magnet. But actually, they do not stop, but penetrate into the magnet and continue right through it.
- If the spacing between two loops carrying parallel currents is 1/2 the loop diameter, this is called a “Helmholtz Pair”. This configuration gives a rather uniform B-field in between the loops.
- When the two loops are near to each other, and the currents are circulating in the same direction, the magnetic fields in between them tend to add.