Rotating mirror for determination of the velocity of light, after Foucault

Parijs Froment, 1863

How to measure the immensely high velocity of light? In the 17th century astronomic observations had shown that the velocity of light was about 300,000 metres/second. In 1850 Foucault (1819-1868) presented the first method which made a real precision measurement possible. Its central element is a fast rotating mirror, driven by compressed air. The centre of rotation is positioned exactly in the centre of a second, circular mirror, which is at a large distance of the first mirror. A beam of light is directed from the first mirror to the second mirror and returns by the same route. In the mean time the first mirror has turned slightly, causing a slight displacement between the incident and reflected beams. The velocity of light can be calculated if the displacement, distance between mirrors and speed of rotation are known.

Administration name

Fysisch Kabinet

Title

Rotating mirror for determination of the velocity of light, after Foucault

Translated title

Rotating mirror for determination of the velocity of light, after Foucault

Creator

[{'date_of_birth': u'', 'role': u'', 'qualifier': '', 'date_of_death': u'', 'creator': 'Froment, Parijs'}]

Object category

03.06

Dating

[{'start': '1863', 'end_precision': u'', 'end': u'', 'start_precision': u''}]

Material

[{'material': 'Mirror'}]

Measurements

[{'notes': u'', 'part': 'geheel', 'type': 'hoogte', 'value': '205', 'unit': 'mm'}, {'notes': u'', 'part': 'voet', 'type': 'lengte', 'value': '200', 'unit': 'mm'}, {'notes': u'', 'part': 'voet', 'type': 'breedte', 'value': '140', 'unit': 'mm'}]

Object number

FK 0299

Inscription

[{'content': u'Froment \xe0 Paris', 'type': 'signatuur'}]

Reproduction reference

[{'reference': '..\\images\\Fysisch\\Gekoppelde afbeeldingen\\FK 0299.jpg'}]