|
:''Not to be confused with Leviton, an electrical manufacturing company.'' Levitron is a brand of levitating toys and gifts in science and educational markets marketed by Creative Gifts Inc. and Fascination Toys & Gifts. The ''Levitron'' top device is a commercial toy under this brand that displays the phenomenon known as spin-stabilized magnetic levitation. This method, with moving permanent magnets, is quite distinct from other versions which use changing electromagnetic fields, levitating various items such as a rotating world globe, model space shuttle or VW Beetle, and picture frame. 750,000 units were sold from 1994 through 1999.〔 == The device == (詳細はpermanent magnetic ring and corresponding magnetic base plate with a ring or alternate geometric configuration. Functional parameters, such as the top rotation rate or top weighting, are stringent. Employing principles of the magnetic field and gyroscopic stabilization, the Levitron induces levitation in its top through a series of interactive steps. The levitated top's stabilizing rotation undergoes natural, gradual slowing, so that the levitation phenomenon fails within four minutes unless external power is supplied to sustain rotation. To levitate the top, a plastic plate is placed on top of the magnetic base, and the top is spun on the plate at between 25-50 rotations per second (1500-3000 rpm). If too slow, the top falls over and slides off sideways; if too fast it does not orient itself to follow magnetic flux as it moves, and slides off. Since it can be difficult to spin the top fast enough by hand, Creative Gifts makes a battery-powered, hand held device to spin the top with an electric motor. Next, the plate is lifted by hand until, if conditions are right, the top rises above it to an equilibrium point. The top must also be weighted with washers of various sizes supplied in the kit. If too heavy it will not rise above the plate; if too light it flies off.〔(【引用サイトリンク】author=Michael V. Berry )〕 After a few minutes, the top falls when air friction slows it below the critical speed. Air temperature, air currents, ground vibration, and power source interruptions also alter the delicate equilibrium necessary to keep the top stable. More expensive laboratory versions can sustain a levitating top indefinitely by sustaining the top rotation actively compensating for aberrations in rotation. The makers of the Levitron have developed a "Perpetuator", which sits under the Levitron and sends out an additional magnetic pulse. The additional force nudges the spinning top enough to maintain a constant speed. With a constant speed, and with the Levitron perfectly level, the Levitron top can spin for longer periods of time. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Levitron」の詳細全文を読む スポンサード リンク
|