Home >> Science & Nature >> Science

How to Build Your Own Helmholtz

Magnetism is fundamental to modern day technologies and is used in devices such as loudspeakers, electromagnets and cassette tape recorders. Critical to the functioning of magnetism-based devices is the electromagnet, which is a magnetic core that is coiled with wire. Although electromagnets can be very powerful, the field produced is often nonuniform. A Helmholtz coil allows the production of a small but uniform magnetic field and simply consists of two copper coils placed in a particular geometry.

Things You'll Need

2 Aluminum rings with a 6-inch radius and 1-inch width
Reel of copper wire
Thermal glue

Instructions

- 1
  Coil the first aluminum ring. The amount of field produced by the Helmholtz coil will be proportional to the number of coil turns placed around the aluminum ring. The equation used calculate the desired field is: B = (4/5)^(3/2) x (Mu0 x n x I ) / R.
  
  B is the magnetic field, Mu0 is the permeability of free space, n is the number of coil turns, I is the current going through the coils, and R is the radius of the aluminum rings (6 inches). Terminate the coil ends with thermal glue to hold them in place.
- 2
  Coil the second aluminum ring and ensure that it has the same number of turns as the first.
- 3
  Place the two coils a distance of 6 inches apart with the centers of the rings facing one another. This is known as the Helmholtz geometry, and when current is passed through the two coils, a uniform field will be produced at the midpoint between the center of the circles.

Science