Understanding Earth's Magnetic Field Angles

Earth acts like a giant magnet, generating a magnetic field that surrounds the planet. This field is crucial for navigation and is characterized by several directional angles. The question asks for the specific angle between the direction of magnetic north and the total magnetic field vector.

Defining Key Magnetic Angles

To understand the answer, let's clarify the terms:

• Magnetic Declination: This is the angle measured in the horizontal plane between the direction of true geographic north and the direction of magnetic north (the direction a compass needle points horizontally). It varies depending on your location on Earth.
• Magnetic Inclination (or Dip Angle): This is the angle between the total magnetic field vector and the horizontal plane. At the magnetic poles, the field is vertical (inclination is 90°), and at the magnetic equator, it is horizontal (inclination is 0°). In most other locations, the magnetic field vector points both horizontally and downwards (in the Northern Hemisphere) or upwards (in the Southern Hemisphere) relative to the horizontal plane.

Analyzing the Question

The question asks for the angle between magnetic north and the total magnetic field. While "magnetic north" typically refers to the horizontal direction a compass points, the angle described is precisely how much the total magnetic field vector deviates from the horizontal plane. This deviation angle is known as magnetic inclination.

Therefore, the angle between the horizontal direction (represented by magnetic north) and the total magnetic field vector itself is the magnetic inclination or dip angle.

Evaluating the Options

• Magnetic declination: This is a horizontal angle relative to true north, not the angle with the total field.
• Magnetic inclination: This is the angle between the total magnetic field and the horizontal plane, matching the description.
• Magnetic total angle: This is not a standard geophysical term.
• Magnetic vertical angle: While inclination relates to the vertical aspect, "magnetic inclination" is the precise and standard term.

Based on these definitions, magnetic inclination is the correct term for the angle between the total magnetic field and the horizontal plane, which is implied by the angle relative to magnetic north.