### Electromagnetism

Schematic of setup

(Click figure to enlarge)

Experimental result: Magnetic field of various coil spacings

(Click graph to enlarge)

## LEEI-37 Helmholtz Coil Magnetic Field Apparatus

Features

• Compact, accurate, and flexible

• Easy to use

• Stable and reliable

Introduction

Helmholtz coil magnetic field measurement is one of the important experiments in general physics teaching, as it teaches students how to measure weak magnetic fields, verify magnetic field superposition principle, and plot magnetic field distribution. Traditionally, Helmholtz coil magnetic field measurement yields relatively large errors with the use of an indicator-type AC voltmeter.

This apparatus adopts an integrated Hall sensor as the detector to detect Helmholtz coil magnetic field. Hall sensors are compact, sensitive, accurate, and flexible to deploy. The output voltage is measured with a DC voltmeter with higher measurement accuracy.

Using this apparatus, the following experiments can be performed (An example of experimental result shown at left):

1. Measure the magnetic field intensities at the points along the axis of a single current-carrying coil

2. Measure the magnetic field distribution along the axis of the Helmholtz coils with different coil spacings

3. Verify the magnetic field superposition principle

4. Plot the magnetic field distributions of a single current-carrying coil and the Helmholtz coils, respectively

Parts and Specifications

 Description Specifications Milli-Teslameter range: 0 - 2 mT, resolution: 0.001 mT DC current supply range: 50 - 400 mA, stability: 1% Helmholtz coil 500 turns, outer diameter: 21 cm, inner diameter: 19 cm Measurement error < 5%

Schematic of setup

(Click figure to enlarge)

Experimental result: Magnetic field of various coil spacings

(Click graph to enlarge)