tag:techtv.mit.edu,:Array/218665980 2008-07-18 11:31:42 -0400 MIT Department of Physics Technical Services Group <p>A 100 uF oil-filled capacitor is charged to 3 KV. This takes approximately 15 minutes, creating a charge on the capacitor that could be lethal. The capacitor is then discharged through a 12" length of 30 gauge bare iron wire.</p><p>When the high voltage current flows though high resistance wire, the bonds between iron molecules are shattered, resulting in a loud bang, a shower of sparks, and a cascade of wispy filaments floating through the air.</p><p>Not all of the charge on the capacitor is disharged through the wire, so a shorting bar must be used to release the remaining charge. </p> 121 tag:techtv.mit.edu,:Array/218606940 2008-06-20 16:53:07 -0400 MIT Department of Physics Technical Services Group <p>A light bulb is placed in series with two copper plates immersed in de-ionized water. Touching the plates closes the circuit, lighting the bulb.</p><p>When kosher salt is dropped into the de-ionized water, the salt dissolves, causing ions to be dispersed throughout the liquid. The free ions allow current to flow through the water, which completes the circuit and lights the bulb.</p><p>Most water we encounter in everyday life is not de-ionized and contains impurities with dissolved ions. This is why we know water as a good conductor, and why we shouldn't use electronic devices around a bathtub, for example.</p> 54