Exploring Magnetic North
Find Magnetic North Using a Magnetometer
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Autor:
The Earth's magnetic field is an invisible yet essential phenomenon used in navigation, geophysics, and various scientific and technological applications. With a smartphone’s magnetometer, this experiment allows students to find magnetic north experimentally and understand how compasses work.
By performing this activity, students will observe how digital sensors measure physical phenomena, analyze the components of a vector field, and connect their findings to a real-world application: orientation on Earth.
➡️ Retrouve cette activité dans l'application FizziQ (Activités > ➕ > Catalogue d'activités)
Concepts Covered:
✔ Earth’s Magnetic Field: Understanding its direction and intensity variations based on location.
✔ Horizontal and Vertical Components of the Magnetic Field: Differentiating their roles and influence on detecting magnetic north.
✔ Magnetic North vs. Geographic North: Learning why they do not coincide exactly.
✔ Using a Digital Sensor: Experimenting with a magnetometer and interpreting its data.
Experiment Steps:
1️⃣ Activate the measurement tool
Open FizziQ and select the Magnetometer instrument.
Enable the measurement of the Y magnetic field component (horizontal).
2️⃣ Observe variations in the magnetic field
Slowly rotate the smartphone while monitoring the Y-component values.
Identify the moment when the Y value is at its maximum—this orientation corresponds to magnetic north.
3️⃣ Compare with a compass
Check if the magnetometer’s north matches a traditional compass reading.
Tilt the smartphone slightly and observe how this affects the Y measurement.
4️⃣ Determine the horizontal magnetic field strength
Properly orient the smartphone and record the horizontal magnetic field value.
Compare this value with theoretical regional data.
Scientific Explanation:
1. Earth’s Magnetic Field
The Earth's magnetic field is a vector field that varies based on location. It is generated by the movement of the Earth's outer core, creating a dynamo effect.
2. Magnetic Field Components
The magnetic field is composed of three axes: X (East-West), Y (North-South, horizontal), Z (Vertical, directed towards the ground or sky depending on latitude). This experiment focuses on the Y-component, which helps identify magnetic north.
3. Difference Between Magnetic and Geographic North
Geographic North aligns with Earth's rotational axis.
Magnetic North is where a compass needle points and shifts over time due to Earth's core movements.
The magnetic declination is the angle difference between them. In France, it ranges from 1° West (Brest) to 3° East (Strasbourg).
4. How a Magnetometer Works
A magnetometer is a sensor that measures the intensity of the local magnetic field. It operates using the Hall effect or magnetic resonance sensors and is built into smartphones for navigation and augmented reality applications.