Magnetic Field
Understanding magnetic fields and their properties.
What is a Magnetic Field?
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. It is produced by electric currents and the magnetic moments of elementary particles. Magnetic fields are often visualized using magnetic field lines.
Magnetic Field Strength (B)
Magnetic field strength, also known as magnetic flux density, is a measure of the strength of a magnetic field. It is measured in Tesla (T) or Gauss (G).
Where:
• F = Magnetic Force
• q = Charge
• v = Velocity of charge
• B = Magnetic Field Strength
• θ = Angle between velocity and magnetic field
Properties of Magnetic Fields
- Magnetic field lines form closed loops; they never start or end.
- The density of field lines indicates the strength of the magnetic field.
- Magnetic field lines emerge from the North pole and enter the South pole of a magnet.
- Magnetic fields exert forces on moving charges and current-carrying conductors.
Sources of Magnetic Fields
| Source | Description |
|---|---|
| Permanent Magnets | Materials that produce their own persistent magnetic fields. |
| Electromagnets | Coils of wire that produce a magnetic field when electric current flows through them. |
| Earth's Magnetic Field | Generated by electric currents in the molten outer core of the Earth. |
| Moving Electric Charges | Any moving electric charge (current) creates a magnetic field around it. |
Frequently Asked Questions
What is the difference between an electric field and a magnetic field?
Electric fields are produced by stationary electric charges and exert forces on other electric charges. Magnetic fields are produced by moving electric charges (currents) and exert forces on other moving electric charges or magnetic materials.
How are magnetic fields used in technology?
Magnetic fields are fundamental to many technologies, including electric motors, generators, transformers, data storage (hard drives), MRI machines, and magnetic levitation (maglev) trains.