Lenz's Law Magic Trick

Abstract

The demonstration of Lenz's law by dropping a powerful magnet down a nonmagnetic metal pipe has become a classic lecture-hall demonstration.1,2 An inexpensive version is packaged as a professional magic trick3 called “Newton's Nightmare.” Combining sleight-of-hand with a demonstration of Lenz's law is a surefire way to heighten student interest. The subsequent student discussion motivated by a desire to understand the magic trick can lead to a memorable physics lesson. This paper will discuss Lenz's law magic and review literature that reveals the subtlety of the physics.

Dramatic (and Simple!) Demonstration of Newton's Third Law

“…A smaller version of this demonstration is available as an inexpensive kit from Penguin Magic. 2 This particular item was actually mentioned in an earlier article 3 in The Physics Teacher. The kit consists of a blue anodized aluminum tube (length 25 cm) with holes that enable viewing, a solid brass-colored cylindrical magnet, and an identical nonmagnetic "dummy" cylinder that has the same mass and appearance as the magnet.…”

“…This method was inspired by a footnote in Ref. 3, which mentions such an experiment but does not elaborate on it.…”

“…Magnetic forces have been utilized before in pedagogical illustrations of Newton's third law. [3][4][5][6][7][8][9][10][11][12] Some of these demonstrations have been primarily qualitative in nature, 3,9,12 while others have used force probes to show experimentally that the forces involved are equal and opposite. 5,7,8 One case used magnetic forces in a static situation to measure the reaction force using a scale.…”

PIVOTS: Service Learning at the Science, Theatre & Magic Boundary

“…Drama, storytelling and re-enactment have proved to be powerful forces in education, have a long tradition of successful application to motivate learners and to clarify difficult concepts in humanities education and can have a profound effect in the teaching of science [15]. (3) Magic as a focus: Magic has been found to be a successful technique to engage students and introduce difficult science concepts from a diverse range of subjects, including Physics [16], Chemistry [17], Computer Science [18,19], Mathematics [20], and for many years as a successful method for improving learning outcomes [21,22], and for students to learn through teaching others [23]. One of the reasons for the success of magic in education is that it often leads to a perceived discrepancy between observation and firmly held beliefs, a teachable moment, which is an effective way to motivate children [14].…”

“…In this two-week multidisciplinary program, teenagers (scholars, [13][14][15][16][17] year olds) learn, explore, and apply scientific principles in the creation and staging of a fantastic day-long performance/adventure that they then share with younger children (apprentices, ages [6][7][8][9][10][11][12]. Inspired by the Harry Potter series of books [1], this culminating event during the second week of the program brings apprentices from Philadelphia, by train, to "enroll" in a fictional "American School of Magic," where the scholars act as guides/teachers (and powerful role models), and deliver science-inspired "magic lessons."…”