Magnetic field strength: The intensity of a magnetic field

The magnetic field strength, also known as magnetic field strength, is a physical quantity that describes the intensity of a magnetic field. It indicates how strong a magnetic field is at a specific point and is measured in units of amperes per metre (A/m). The magnetic field strength is a key parameter in electrical engineering, magnetism and physics.

What does the magnetic field strength describe?

The magnetic field strength is a measure of the effect of a magnetic field. It describes the forces that act on an electric current or a magnetic material in this field. It is directly linked to the electric current and the geometric arrangement of the current conductor:

H = I / (2πr)

Where:

• H: Magnetic field strength (in A/m)
• I: Current strength (in amperes, A)
• r: Distance from the conductor (in metres, m)

This formula shows that the field strength increases with the current strength and decreases with the distance from the conductor.

Difference between magnetic field strength and magnetic flux density

Magnetic field strength ( H ) and magnetic flux density ( B ) are closely related, but describe different aspects of a magnetic field:

• Magnetic field strength (H): Describes the intensity of the magnetic field regardless of the material. It is a cause for the formation of the magnetic field.
• Magnetic flux density (B): Depends on the magnetic field strength and the material properties and is measured in Tesla (T). It describes the effect of the magnetic field in the material.
• The relationship between the two variables is: ( B = μ cdot H ), where ( μ ) is the permeability of the material.

Properties of the magnetic field strength

• Vectorial: The magnetic field strength is a directed quantity and has both a strength and a direction.
• Field lines: The direction of the field strength follows the field lines of a magnetic field, which run from the north to the south pole.
• Material-independent: The magnetic field strength does not depend on the magnetic properties of the material in which it is measured.

Applications of magnetic field strength

Magnetic field strength is used in many areas of science and technology:

• Electrical engineering: For calculating magnetic fields in coils, transformers and electric motors.
• Magnetic field measurement: Magnetometers measure the field strength to analyse magnetic fields in industry or nature.
• Medical technology: In magnetic resonance imaging (MRI), the field strength is used to generate high-resolution images.
• Energy transmission: Magnetic field strengths are used in induction systems such as wireless chargers.

Interesting facts about magnetic field strength

Did you know that the Earth's magnetic field has a magnetic field strength of around 25 to 65 microtesla? In comparison, a typical MRI scanner generates magnetic fields with a strength of up to 7 Tesla, which corresponds to a magnetic field strength of around 5.6 million amperes per metre.