<P> The primary break rate of sparking Tesla coils is slow compared to the resonant frequency of the resonator - topload assembly . When the switch closes, energy is transferred from the primary LC circuit to the resonator where the voltage rings up over a short period of time up culminating in the electrical discharge . In a spark gap Tesla coil, the primary - to - secondary energy transfer process happens repetitively at typical pulsing rates of 50--500 times per second, depending on the frequency of the input line voltage . At these rates, previously - formed leader channels do not get a chance to fully cool down between pulses . So, on successive pulses, newer discharges can build upon the hot pathways left by their predecessors . This causes incremental growth of the leader from one pulse to the next, lengthening the entire discharge on each successive pulse . Repetitive pulsing causes the discharges to grow until the average energy available from the Tesla coil during each pulse balances the average energy being lost in the discharges (mostly as heat). At this point, dynamic equilibrium is reached, and the discharges have reached their maximum length for the Tesla coil's output power level . The unique combination of a rising high - voltage radio frequency envelope and repetitive pulsing seem to be ideally suited to creating long, branching discharges that are considerably longer than would be otherwise expected by output voltage considerations alone . High - voltage, low - energy discharges create filamentary multibranched discharges which are purplish - blue in colour . High - voltage, high - energy discharges create thicker discharges with fewer branches, are pale and luminous, almost white, and are much longer than low - energy discharges, because of increased ionisation . A strong smell of ozone and nitrogen oxides will occur in the area . The important factors for maximum discharge length appear to be voltage, energy, and still air of low to moderate humidity . There are comparatively few scientific studies about the initiation and growth of pulsed lower - frequency RF discharges, so some aspects of Tesla coil air discharges are not as well understood when compared to DC, power - frequency AC, HV impulse, and lightning discharges . </P> <P> Today, although small Tesla coils are used as leak detectors in scientific high vacuum systems and igniters in arc welders, their main use is entertainment and educational displays . </P> <P> Tesla coils are displayed as attractions at science museums and electronics fairs, and are used to demonstrate principles of high frequency electricity in science classes in schools and colleges . </P> <P> Since they are simple enough for an amateur to make, Tesla coils are a popular student science fair project, and are homemade by a large worldwide community of hobbyists . Builders of Tesla coils as a hobby are called "coilers". They attend "coiling" conventions where they display their home - made Tesla coils and other high voltage devices . Low - power Tesla coils are also sometimes used as a high - voltage source for Kirlian photography </P>

Where do you usually find a tesla coil