Determination of the earth's magnetic field

Principle

A constant magnetic field, its magnitude and direction known, is superimposed on the unknown earth magnetic field. The earth-magnetic field can then be calculated from the magnitude and direction of the resulting flux density.

Benefits

• Particularly homogeneous magnetic field and high flux density due to large Helmholtz coil diameter
• Setup with precalibrated teslameter does not require additional magnets and coils for calibration

Tasks

1. The magnetic flux of a pair of Helmholtz coils is to be determined and plotted graphically as a function of the coil current. The Helmholtz system calibration factor is calculated from the slope of the line.
2. The horizontal component of the earth-magnetic field is determined through superimposition of the Helmholtz field.
3. The angle of inclination must be determined in order to calculate the vertical component of the earth-magnetic field.

Learning objectives

• Magnetic inclination and declination
• Isoclinic lines
• Isogenic lines
• Inclinometer
• Magnetic flow density
• Helmholtz coils