The Solenoid

Initializing live version
Download to Desktop

Requires a Wolfram Notebook System

Interact on desktop, mobile and cloud with the free Wolfram Player or other Wolfram Language products.

A solenoid consists of an insulated wire twisted around a metallic rod (typically iron). It yields a magnetic field as long as a current runs through the windings. The strength of the magnetic field is proportional to the number of turns of wire. Its advantage over a permanent magnet is that the intensity of the magnetic field can be varied and turned on and off. In the graphic, as electricity is supplied by a battery, the nail and the clip are attracted to the solenoid.

Contributed by: Enrique Zeleny (March 2011)
Open content licensed under CC BY-NC-SA



The strength of the magnetic field at an interior point of a large solenoid is constant, given by , where is the permeability of free space, the number of windings, and the intensity of the electric current.

Feedback (field required)
Email (field required) Name
Occupation Organization
Note: Your message & contact information may be shared with the author of any specific Demonstration for which you give feedback.