Michael Faraday's magneto-optical apparatus

The apparatus, consisting of an electromagnet, used by Michael Faraday in a ground-breaking experiment showing that light and glass are affected by magnetism.

  • Faraday magneto-optical

    MIchael Faraday's magneto-optical apparatus.

    Credit: Paul Wilkinson
  • Date

  • Place made

    Basement laboratory at the Ri

  • Alternative name

    Magneto-optical apparatus
  • People

  • Materials

    Glass, copper, cotton, iron

  • Key words

    Michael Faraday,  experiment, electricity, magnet, magnetism, optical, apparatus, light, Faraday Theory


Michael Faraday was determined to prove that all matter is magnetic, and that electricity, magnetism and light are similar kinds of things.  His experiment was carried out in 1845 in the former servants’ hall in the basement of the Royal Institution’s building in 21 Albemarle Street, London.  This is now known as his magnetic laboratory.  He placed a dense piece of glass on the poles of the electromagnet, and then passed polarised light (light that travels in a single plane rather than in all directions) through the glass.

When he turned on the electric current, the state of polarisation of the light changed, confirming that both light and glass possessed magnetic properties.  He wrote in his notebook: ‘I have at last succeeded in .... magnetising a ray of light’.  Now called the ‘Faraday effect’, this was a critical experiment in Faraday’s development of the field theory of electro magnetism, which is one of the cornerstones of modern physics and communication theory.

More images

  • Michael Faraday magneto-optical apparatus

    Michael Faraday magneto-optical apparatus.

    Credit: Paul Wilkinson

  • Michael Faraday's magneto-optical apparatus

    Michael Faraday's magneto-optical apparatus.

    Credit: Paul Wilkinson

Related pages

Become a member

Benefit from free and better than half-price tickets, special offers and access to the CHRISTMAS LECTURES ticket ballot.

Join todayGo