The Stun Gun
Most clothing won't save you from a nasty shock if someone turns a stun gun on you. How can that be, since metal isn't touching skin directly? Before looking at the physics involved in how stun guns penetrate clothing, it's important to understand what exactly they are and how they work.
"Stun gun" is a term used to describe any of a wide variety of weapons known as conducted energy devices (CEDs). They are also often referred to as Tasers, after the most prominent manufacturer of CEDs, and they use high-voltage, low-amperage electric currents to "stun" a person. They are sometimes used by civilians for self-defense and often issued to police officers as a "nonlethal" mode of subduing a perpetrator. However, the question as to whether they are truly nonlethal has been under scrutiny for some time, since deaths have been reported widely by various organizations, such as Amnesty International.
How Stun Guns Work
According to the U.S. Department of Justice's Office of Justice Programs, when a person is hit by a Taser or other type of CED weapon, they experience involuntary muscle contractions that vary in severity depending on the length of application of the electricity to the person's body. Stun guns generate around 50,000 to 300,000 volts of electricity, depending on the model. When someone's body is shocked by that kind of voltage, the resulting muscle spasms incapacitate the person.
Getting Through Clothing
So, how does that electricity pass through clothing and into the body? For one type of Taser, which fires two barbed darts attached to wires using compressed nitrogen, the answer is easy--the barbs penetrate clothing and pierce the skin, causing a quick connection. But as for the two-pronged models many people carry in their purses or back pockets when walking alone on a dark city street, the answer involves a little bit of basic physics.
When the two pairs of electrodes on either side of a nonprojectile stun gun are pressed against a clothed person's body, this completes an electrical circuit, enabling a discharge of electricity into the body. The ability of a CED like the stun gun to penetrate clothing has to do with a simple physical rule--resistance. In lay terms, resistance is simply a substance's ability to withstand--"resist"--electrical voltage. For instance, the power cords in your home are most likely coated in rubber or some kind of plastic polymer, which have excellent resistance to electricity and keep the current inside the cord. With the voltage of stun guns and other CEDs being so high, their ability to send electricity through most types of clothing is nearly as effective as if the clothes weren't there. The body itself is an excellent conductor--which means it's good at letting electrical currents flow through it--and that, combined with the inadequacy of most types of clothing to resist voltages between 50,000 to 300,000 volts, is why stun guns can work through clothes in most cases. Thick leather jackets, layers of clothing over 2 inches thick and rubberized raincoats are the only exceptions, although they don't guarantee safety against a high-voltage stun gun.
Stun guns, while often touted as nonlethal, are very dangerous and are not considered 100-percent safe alternatives to firearms. They are illegal in many states. If you own one or plan on getting one, treat it with respect. And if a police officer points one in your direction, keep your hands where the officer can see them and obey his instructions to avoid a potentially life-threatening shock.