# What are Helmholtz coils?

Helmholtz coils are a pair of identical circular coils of wire, placed parallel to each other and equidistant from each other. They are named after their inventor, German physicist Hermann von Helmholtz. The coils are known for producing a nearly uniform magnetic field in the space between them when an electric current flows through them in the same direction. The magnetic field produced is used for various scientific and industrial applications.

# How do Helmholtz coils work?

Helmholtz coils work on the principle of the superposition of magnetic fields. The current flowing in each coil creates its own magnetic field, which can be thought of as a series of concentric circles around the axis of the coil. When the two coils are placed parallel to each other and their axes are aligned, the magnetic fields of each coil add up to produce a uniform magnetic field in the space between them. This uniform magnetic field is ideal for applications where a constant magnetic field is required.

# Applications of Helmholtz coils

Helmholtz coils have numerous applications in scientific research, engineering, and industry. They are used in experiments related to magnetism, such as studying the magnetic properties of materials, measuring the earth’s magnetic field, and investigating the effects of magnetic fields on living organisms. Helmholtz coils are also used in the calibration of magnetic sensors and in the testing of electronic equipment for electromagnetic compatibility. In industry, Helmholtz coils are used to test the magnetic shielding effectiveness of materials.

## Example: Magnetic field measurements

One of the most common applications of Helmholtz coils is in the measurement of magnetic fields. Helmholtz coils are used to produce a uniform magnetic field, which can be calibrated to a known value. Magnetic sensors such as Hall effect sensors can be placed in the center of the coils to measure the magnetic field strength. By measuring the response of the sensor to the magnetic field, the strength of an unknown magnetic field can be determined. This technique is used in a range of fields, including geology, physics, and engineering.