WEBVTT

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With a slow stepper motor, we drive a magnet that rotates in front of a coil

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Coil connected to a needle galvanometer: 0 in the center in order to visualize the direction and the amplitude of the induced current in the coil!

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When the North Pole approaches, the amplitude becomes maximum

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Maximal also when the South approaches; the tension is, on the contrary, opposite in direction!

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At idle, it is well observed at which positions of the magnet with respect to the coil correspond the maximum amplitudes! As well as reversal of meaning!

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At higher speeds, the rhythm, the beat frequency of the needle increases!

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The stepper motor generated a slow-moving noise ...

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We replace the needle galvanometer with our LCD oscilloscope

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IF the signal is symmetrical positive and negative it is far from a sinusoid because our magnet is not rounded as on the animations of the course ...

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This time a cylindrical magnet mounted on a motor!

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Here finally a sinusoid!

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The amplitude increases when the speed increases, it is the opposite of the width (the period) which decreases ...

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The magnet is not well concentric, not round, the sinusoid is irregular ... Impossible in industry I reassure you!

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This imperfection of the centering makes us understand the importance of the adjustments in real electrical machines!