A wire dying a violent death
Spark gap switch and capacitor bank
If too much current (current is proportional to power) is routed through a wire, the wire can get hot enough to melt off the insulation. If way too much current is routed through a wire, the wire can get red hot and even melt. This is how fuses work. This is also how electrical fires get started inside the walls of houses. If the current-carrying capacity of the wire is exceeded by several orders of magnitude, the wire can be completely vaporized, often explosively. This is the idea behind exploding bridge wires.
In order to explode a wire, a large capacitor (or bank of capacitors) is charged up to a relatively high voltage. (Capacitors are kind of like rechargable batteries, in that they can store up an electrical charge and then give that charge back at a later time. Capacitors differ from batteries since capacitors can give that charge back very quickly.) Once the capacitor is charged, it is then discharged through a very thin wire. If the capacitor is large enough, and the wire is thin enough, and the capacitor is capable of giving back the energy quick enough, the wire will be explosively vaporized, causing a bright flash of light (as shown in the photos) and a loud report (similar to a firecracker, but often substantially louder).
If the wire to be exploded is placed between sheets of card
stock, when the wire explodes, the copper vapor (if you are
exploding a copper wire)
will combine
with the various gasses in the air to form various copper compounds,
which are deposited on the card stock in a blast pattern, two of which are
shown below. Click on either of the images to see a larger
version. The actual blast patterns are on pieces of 9" x 12" card stock.
Note that often the blast rips holes in the
card stock.
Exploding bridge wires are used in applications where it is necessary to have extremely precisely timed explosions, such as in nuclear detonators.
Unfortunately, because it is necessary to charge a large capacitor to a high voltage in order to explode a wire, this project is inherently dangerous. (Getting your finger where the wire is supposed to be could result in a really nasty shock, if you are lucky. If you are unlucky, then it can result in, um, unnecessary funeral expenses.) For this reason, information on how to build the necessary circuitry will not be given here. If experienced experimentors are interested in persuing this project, please contact me via e-mail, with your name, age, and how much experience you have with electronics and high voltage.
