The classic jumping ring apparatus consists of a coil with an iron core that extends out of the coil. A copper or aluminum ring placed over the iron core jumps upward when AC power is applied to the coil. In this paper we will examine a modified design of the jumping ring apparatus, called the “long-coil design.” It allows the ring to jump upward or downward, depending on the starting position of the ring. These features shed significant light on the study of the force that causes the ring to jump.
References
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James Lincoln has two videos with the PASCO Ring Launcher: (1) “Jumping Ring Apparatus
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See, for example,
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University of Manchester Virtual Laboratory video, “
Jumping Rings Demonstrations
,” https://www.youtube.com/watch?v=T9PflsLZqY8, accessed Dec. 16, 2016. Shows various ring jumps and levitation, including demonstration that chilled rings jump higher than room temperature rings. Also shows a light bulb lighting up, brightness increases lower on the core, showing the emf decreases along the core, but gives erroneous picture of the magnetic field around the core. At the end of the video it shows a thin wafer ring that doesn’t jump by itself but is attracted to another ring placed above it on the iron core. No explanation is offered of this effect on the video, but it shows the attraction of parallel currents as discussed in the text.© 2018 American Association of Physics Teachers.
2018
American Association of Physics Teachers
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