Testing Magnetic Field Strength With a Gaussmeter
Calculate the baseline or original voltage. This can be done using a gaussmeter, also known as a magnetometer or an EMF detector (electromagnetic field detector), which is a hand-held device that measures the strength and direction of a magnetic field strength. They are readily available to buy and simple to use. The gaussmeter method is suitable for teaching middle school and high school students about magnetic fields. Here’s how to start using one:
Set the maximum voltage to be read at 10 volts DC.
Read the voltage display with the meter away from a magnet. This is the baseline or original voltage, represented as V0.
Touch the meter’s sensor to one of the magnet’s poles. On some gaussmeters, this sensor, called a Hall sensor, is built into an integrated circuit chip, so you touch the magnet’s pole to a sensor.
Record the new voltage. Represented by V1, the voltage will either go up or down, depending on which pole of the magnet is touching the Hall sensor. If the voltage goes up, the sensor is touching the magnet’s south-seeking pole. If the voltage goes down, the sensor is touching the magnet’s north-seeking pole.
Find the difference between the original and the new voltage. If the sensor is calibrated in millivolts, divide by 1,000 to convert from millivolts to volts.
Divide the result by the sensitivity value of the sensor. For example, if the sensor has a sensitivity of 5 millivolts per gauss, you would divide by 5. If it has a sensitivity of 10 millivolts per gauss, you would divide by 10. The value you receive is the field strength of the magnet in gauss.
Repeat to test the field strength at varying distances from the magnet. Place the sensor at a series of defined distances from the magnet’s pole and record the results.