how does a magnetic stirrer work?

Question

It would help if it came with some illustration.

Answer 1

A magnetic stirrer consists of a small bar magnet (or stir bar), which is normally coated in a plastic such as PTFE and a stand or plate containing a rotating magnet or stationary electomagnets creating a rotating magnetic field. Often, the plate can also be heated. During operation of a typical magnetic stirrer, the bar magnet (or flea) is placed in a vessel containing a liquid to be stirred. The vessel is set on top of the stand, where the rapidly rotating magnetic field causes the bar magnet to rotate.

Arthur Rosinger of Newark, New Jersey, U.S.A. obtained US Patent 2,350,534, titled Magnetic Stirrer on 06 June 1944, having filed an application therefor on 05 October 1942. Mr. Rosinger's patent includes a description of a coated bar magnet placed in a vessel, which is driven by a rotating magnet in a base below the vessel. Mr. Rosinger also explains in his patent that coating the magnet in plastic or covering it with glass or porcelain makes it chemically inert.