Air Core Solenoid - Magnetic Field Generator w/Activity Guide
It is used to provide an external magnetic field where required, and to change the rate of magnetic flux that is passing through a coil. It consists of a durable plastic spool that has windings of insulated copper wire. Each end plate has a brass binding post, and is RoHS Certified.
The reason behind the open core is that shortly after electromagnets were invented in the 1820's, researchers found that an air gap in the electromagnet resulted in the magnetic field being concentrated towards the interior, rather than the exterior. This allowed a core of different materials to be moved, based on the strength of the electromagnet, allowing for the core to be put to use performing work. One of the most common uses in modern times is in electronic locks.
The air core solenoid measures 15.5x10.1x10.1cm (6.1x4x4 inches), and comes with an activity guide.