tag:techtv.mit.edu,:Array/218853600 2008-10-10 14:24:44 -0400 MIT Department of Physics Technical Services Group Two carts are connected together on an air track with a spring. Under bright lights you can see the coupled oscillation of the carts back and forth, but under black lights you can see that the center of mass moves at a constant velocity. 103 tag:techtv.mit.edu,:Array/218832640 2009-04-16 11:06:25 -0400 MIT Department of Physics Technical Services Group A laser is directed at an adjustable single slit and then a pinhole and the resulting diffraction patterns can be seen on a screen. <br><br> A laser directed at two slits spaced closely next to each other creates an interference pattern within the diffraction pattern. Shining lasers of different wavelength light shows how the wavelength affects the interference and diffraction patterns. 146 tag:techtv.mit.edu,:Array/218813680 2009-06-01 15:48:40 -0400 MIT Department of Physics Technical Services Group Two or more air carts are connected by springs on an air track. When this system is at resonant frequency, symmetrical patterns called <a href="http://en.wikipedia.org/wiki/Normal_mode">normal modes</a> appear. The normal modes are shown in both undriven and driven cases. In the undriven examples, the normal modes are found by placing the carts at certain distances from each other and then letting them oscillate. In the driven examples they are found by driving the system with a motor, and varying the frequency until the normal mode patterns appear. Both of these methods are shown for systems of two, three, and five coupled carts. 459 tag:techtv.mit.edu,:Array/218794400 2009-06-30 14:12:10 -0400 MIT Department of Physics Technical Services Group A wire frame is dipped in bubble solution and placed in front of a speaker. At certain frequencies, the soap film oscillates in symmetrical patterns called <a href="http://en.wikipedia.org/wiki/Normal_mode">normal modes</a>.<br><br> A light is reflected off the soap film through a lens onto the wall to show these normal modes as the frequency of the function generator is increased. The first set of normal modes occur at frequencies lower than we can hear with our ears, which is why you can't hear the speaker in the video until the frequency is increased. 268 tag:techtv.mit.edu,:Array/218775420 2009-07-07 11:45:24 -0400 MIT Department of Physics Technical Services Group A long beaded chain is looped over a motor pulley. When the motor is turned on, a disturbance in the chain causes waves to propagate through it. When the motor is brought up to full speed and the chain is knocked off the pulley it will maintain its shape for a few seconds and appear to "walk". 87