A v. Waltenhofen’s pendulum by Kipp and sons Amsterdam, to demonstrate the dampening effect of induction, with a solid and a toothed piece of copper.
Waltenhofen showed how to demonstrate the effect of eddy currents induced in a piece of copper moving in a magnetic field. His apparatus consists of a pendulum having a curved strip of copper at its lower end and arranged so that it hangs between the poles of an electromagnet. So long as no magnetic flux passes through the copper, the pendulum swings freely, but as soon as the electromagnet is switched on the oscillations of the pendulum are heavily damped and die away rapidly.
Measuremens: 46 x 22,5 x 22,5 cm.
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Van Leest Antiques
Van Leest Antiques, based in Utrecht in the Netherlands, specialises in antique scientific and medical instruments. Their collection covers mainly scientific and medical antique instruments: barometers, globes and planataria, nautical instruments, anatomical models, and pharmacy items. Toon Van Leest travels regularly in Europe and visits trade fairs, auctions, and antique dealers to collect stock and to find pieces to fulfil his clients' unusual requests.
As well as being an avid antique collector and dealer, Toon Van Leest is also a dentist. He believes that antiques are a stable investment, not reliant on trends or fashion, and have truly lasting value. Above all, he says, antiques are timeless and never lose their beauty.
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