![]() ![]() This point was, however, puzzling, and in his paper Foucault draws the attention of “géomètres” (as mathematicians were called at that time) to solve the problem in a more rigorous way." The problem is more complicated at lower latitude, but Foucault rightly convinced himself that the angular speed of the veering of the swing plane should be proportional to the sine of the latitude. He was inspired by the observation of a thin flexible rod on the axis of a lathe, which keeps oscillating in a constant plane in spite of the rotation of its support. Foucault checked that the rotation of the support has indeed negligible effect on the plane of rotation. As he explains in his report, the principle is easy to understand at the pole: by inertia the plane of oscillation remains constant with respect to an inertial reference frame, so that in a sidereal day (23 h 56 min) it rotates or veers through a full 360◦with respect to the Earth, in the opposite direction. "In 1851 Léon Foucault first described his famous pendulum experiment in the Comptes rendus. Shaw, Fiber-optic gyroscopes: in harsh, confining environments this advanced gyroscope, a close cousin to the ring laser gyro, offers great advantages, IEEE Spectrum 23 (1986), 54-60 G E Stedman, Ring-laser tests of fundamental physics and geophysics, Reports on Progress in Physics 60 (1997), 615 ![]() Rotation rate $\Omega_E$ (Kim and Shaw 1986). Then the two beams meet at the detectors, which just records a shift $\Delta$ of interference fringes between them. So a light source (nowadays a laser) sends two beams across the optical loop (the beam is reflected by the mirrors, represented by the grey rectangles): one in one direction and the other one in the other direction. The principle is rather simple and can be demonstrated on the following simple sketch (kudos to Krishnavedala on Wikipedia: I just converted the image to PNG) ![]() They are based on the optical brother of the Coriolis force, called the Sagnac effect. Mechanical gyroscopes have been completely replaced by laser ones in all inertial system of planes, rockets, etc. But why would anybody bother when it is so much easier to build a Foucault pendulum? Laser gyroscopes ![]() I am not aware of any purpose-built gyroscope to test Coriolis forces. Thus I reckon you would need a gyroscope way bigger than the mass-produced ones. This is why Foucault pendulums have to be sizeable (the smallest I am aware of has a string about 5 meters long). It is well-known that this force is weak on small system, by which I mean it is easily overwhelmed by non-inertial forces such as friction, viscosity, etc. Please note that this feature is not possible for Gen 1 and Gen 2 Stages Power meters, which do not have a gyroscope within the electronic components.For an observer at the surface of the Earth, the Coriolis force would be responsible of moving the gyroscope axis of rotation.
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