Measuring the Magnetic Field Vector of Earth

Abstract

The magnetic field of Earth, B e, is an intriguing topic in the introductory physics curriculum that engages students’ curiosity and inspires numerous speculations about the nature of this phenomenon. There are several methods for measuring Earth’s magnetic field. Probably, the most widespread and visual method of measuring the field in student lab experiments utilizes a tangent galvanometer. Recently, PASCO scientific suggested to use a magnetic field sensor for this goal, in a procedure where a magnetic field sensor combined with a rotary motion sensor is rotated in a 2-D plane containing the magnetic field vector of Earth. In this case, the magnetic field detected by the magnetic field sensor is a component of the magnetic field vector oriented relative to the direction of the magnetic field sensor probe (radial component of magnetic field). This means that the detected magnetic field considered as a function of the angle of rotation of the sensor will be a sinusoidal function. The amplitude of this function is the magnitude of Earth’s magnetic field. In conducting this experiment, initially the sensor is set to zero by placing it in a Zero Gauss Chamber (mu-metal). The equipment setup of the experiment is depicted in the figure shown in Ref. 9. The described experiment requires the use of a dip needle that is a compass pivoted to move in the plane containing the magnetic field vector of Earth. The dip needle shows the dip angle θ (inclination) that Earth’s magnetic field makes with the horizontal. Besides the previously mentioned devices, this experiment requires the use of an aluminum table clamp, adjustable angle clamp, and angle indicator to ensure proper alignment of the rotary motion sensor in a 2D plane containing the magnetic field vector.