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The National MagLab is funded by the National Science Foundation and the State of Florida.

Magnetic Field of a Solenoid

You can create a stronger, more concentrated magnetic field by taking wire and forming it into a coil called a solenoid.

Magnetic fields are produced by electric currents. A current-carrying wire will generate around it a circular magnetic field in accordance with the right hand rule.

You can create a stronger magnetic field by forming the wire into a coil. The field is more concentrated in the center of the loop than outside the loop. By adding more loops to a coil, you create an increasingly stronger magnetic field. This is known as a solenoid, demonstrated here:


  1. Observe the coil of wire connected to a battery in a simple circuit. Not the coil is embedded in a table covered with iron filings.
  2. Push the power button to close the switch and complete the circuit.
  3. See how the iron filings rearrange themselves according to the magnetic lines of force, or flux lines. Note the filings are concentrated in the center of the solenoid.
  4. Click the "show field lines" button to show the magnetic fields generated by the solenoid.

When the copper solenoid is connected to a battery, it becomes an electromagnet. The ferromagnetic iron filings allow us to physically see the otherwise invisible magnetic fields that surround us every time current travels through a coil of wire.