tag:techtv.mit.edu,:Array/219071840 2008-06-26 16:47:33 -0400 MIT Department of Physics Technical Services Group <p>A long length of wire is suspended horizontally between the poles of a magnetron magnet. When a large current from a 12V storage battery is passed through the wire, the wire jumps out of the magnetic field. When the direction of the current is switched, the wire jumps the opposite direction.</p><p>The magnetron magnet in this demonstration was originally used in MIT's groundbreaking research developing radar during and after World War II. Microwave emitting <a href="http://en.wikipedia.org/wiki/Cavity_magnetron">cavity magnetrons</a> need strong magnetic fields, which were often created by powerful permanent magnets like the one used in this demo. </p> 37 tag:techtv.mit.edu,:Array/219043540 2009-01-16 16:22:08 -0500 MIT Department of Physics Technical Services Group Paper confetti is placed atop a <a href="http://en.wikipedia.org/wiki/Van_de_Graaff_generator">Van de Graaff generator</a> and flies off when the grounding rod is removed. <br><br> When turned on, a Van de Graaff generator builds up lots of negative charge on its large metal sphere. A grounding rod is used to protect the demonstrator and control the amount of charge. When the paper confetti is place on the sphere the charge jumps onto it, but since paper is an insulator, the charge cannot move and sticks to the inner side of the paper. Since there is more negative charge also on the sphere, the negatively-charged paper will be repelled away. <br><br> The Van de Graaff generator was developed by <a href="http://en.wikipedia.org/wiki/Van_de_Graaff_generator">Robert J. Van de Graaff</a>, an MIT professor. 0 tag:techtv.mit.edu,:Array/219022720 2009-06-03 15:26:02 -0400 MIT Department of Physics Technical Services Group Odd-shaped objects with their centers of mass marked by orange paint are thrown. While the objects appear to follow very wobbly trajectories when viewed under bright lights, under black lights you can see that their centers of mass travel in smooth parabolas. <br><br> Then center of mass is not necessarily in the center of an object, as demonstrated by the last object in the video (a weighted disk). 91