### Electromagnetism

Schematic of experimental setup

1. Digital meter, 2. Current source, 3. Helmholtz coil, 4. Magnetoresistance sensor, 5. Small rotational stage, 6. Large rotational stage

Schematic of geomagnetic field

Sensor output vs magnetic field strength

## LEEI-47 Magnetoresistive Sensor & Measuring Earth's Magnetic Field

Features

• Rotary base plate with adjustable level

• High sensitivity magnetoresistive sensor

• Horizontal/vertical components and declination of the earth's magnetic field measurement

Introduction

The earth's magnetic field as a natural magnetic source has important applications in military, aviation, marine, industrial, medical, and scientific research. This instrument uses a new type of Permalloy magnetoresistance (MR) sensor to measure the parameters of the geomagnetic field. Through the experiments, students can learn how to calibrate a magnetoresistive sensor and use it to measure the horizontal and vertical components of the earth's magnetic field and its declination angle.

This instrument is designed with the following features:

1. The base plate can be freely rotated and adjusted in horizontal and vertical directions

2. The magneto-resistance sensor has a high sensitivity (50 V/T) with a resolution up to 10-7~10-8 T

3. The instrument can be used to measure the horizontal component, strength, and direction of a magnetic field

Using this instrument, the following experiments can be accomplished:

1. Measure weak magnetic fields using a magnetoresistive sensor

2. Measure the sensitivity of a magneto-resistance sensor

3. Measure the horizontal and vertical components of the geomagnetic field and its declination

4. Calculate the geomagnetic field intensity

Parts and Specifications

 Description Specifications Magnetoresistive sensor working voltage: 5 V; sensitivity: 50 V/T Helmholtz coil 500 turns in each coil; radius: 100 mm DC constant current source output range: 0 ~ 199.9 mA; adjustable; LCD display DC voltmeter range: 0 ~ 19.99 mV; resolution: 0.01 mV; LCD display

Schematic of experimental setup

1. Digital meter, 2. Current source, 3. Helmholtz coil, 4. Magnetoresistance sensor, 5. Small rotational stage, 6. Large rotational stage

Schematic of geomagnetic field

Sensor output vs magnetic field strength