How to Measure Magnetic Field

Learn how to easily measure magnetic field.  With today’s smart phone technology, all you need to measure the strength of any magnetic field is built right into most phones.

Both iPhones and Android Phones allow measurement of magnetic fields using only the phone and a free app.  There are several apps available to measure magnetic field.  The iPhone options did not appear as easy to use as the Android options.  For this reason this article will focus on how to measure magnetic field with an Android Phone.  The phone we used for testing is the Samsung Galaxy Note 3.  It has nearly the same sensors as the Samsung Galaxy S4 and Galaxy S5 phones.  The Galaxy S4 has a Geomagnetic Sensor which detects magnetic field intensity.  The Galaxy Note 3 has a Yamaha YAS532 Magnetometer sensor.  These sensors are used with the built-in accelerometer to find the position of the Earth’s true north so the phone knows its orientation so it can adjust the screen position.  The phone also uses this sensor to help find its position, even if the GPS feature is turned off.  The magnetic sensors, of course can do much more.  The app-makers tapped into this power to provide the raw magnetic field data to the user.

  • Use the magnetometer sensor in an Android

Magnetic Experiment Items Needed

  • Android Smartphone with magnetic sensor
  • Magnetic Measurement App – We used “Android Sensor Box”
  • A Magnetic Field to measure
  • A magnet (optional)

Instructions on how to Measure Magnetic Field

  • Step 1

    Android SensorObtain and install the app on the smartphone.  We used the Android Sensor Box app which is free.  This app also has more modules including a temperature sensor, pressure sensor, sound sensor, light sensor and more.  There are other free magnetic sensor apps available.  Go to the Google Play store and search for “magnetic sensor”.  The search results will bring up a list of options with different ratings.

  • Step 2

    how to measure magnetic fieldClick on the app icon to start the app.  You will see 9 different icons.  The bottom center icon is a red magnet.  Click on the magnet to open the magnetic sensor module.

  • Step 3

    magnetic field meter

    A computer hard drive has a strong magnetic field

    Move the phone around the room or outside and watch how the readings change.  Move the phone near the magnet to see how it reacts.  Speakers and older phones are also great places to take a magnetic field reading.  The app reads magnetic fields in the unit Teslas, which is a SI unit for magnetic field.  The residual magnetic field of the Earth at 0° latitude, 0° longitude is 31.869 µT.  How do your results look?  Did using the phone app help in understanding how to measure magnetic fields?