"Magnet electromotor", after Christian Ernst Neeff (1839)

Haarlem W.M. Logeman

In 1831 Michael Faraday discovered that the change in a magnetic field can generate an electric current in a nearby conductor, for example a copper wire. In 1839, the German physicist Christian Ernst Neeff devised this apparatus, so that the electromagnetic field could also be studied in air at reduced pressure. It consists of a base with a coil and a contact breaker, on which a glass bell-jar fits. A coil behaves like a magnet as soon as a current runs through it. The current is regularly interrupted by means of the contact breaker. Each time, this causes an electric impulse, which discharges with a spark. Because of the high frequency of the contact breaker, the spark discharges take place so fast, that you cannot see them separately, but you see them as a continuous arc of light. When the air in the glass bell-jar is sucked away for a large part, this arc of light appears to become six to eight times as large.

Administration name

Fysisch Kabinet


"Magnet electromotor", after Christian Ernst Neeff (1839)

Translated title

"Magnet electromotor", after Christian Ernst Neeff (1839)


[{'date_of_birth': u'', 'role': u'', 'qualifier': '', 'date_of_death': u'', 'creator': 'W.M. Logeman, Haarlem'}]

Production notes



[{'material': 'brass'}]

Object number

FK 0692

Reproduction reference

[{'reference': '..\\images\\Fysisch\\Gekoppelde afbeeldingen\\FK 0692.jpg'}]