What Causes A Light To Strobe

Rapid bursts of light cause the phenomenon of strobing.

Developed by scientist Dr. Harold Edgerton early in the 20th century, and known primarily for their “oh, man — wow” factor in dance clubs, stroboscopes (strobe lights) were originally used in high-speed photography. Strobes have evolved into frequently used elements in entertainment areas as well as becoming vital mainstays in the security, law enforcement and rescue fields.

Strobes Appear to Slow Motion

A strobe light makes objects moving at normal speed appear to be moving in slow motion. The term “strobe light” is generally used to describe any flashing light source that accomplishes that effect. A stroboscope pulses a strong but brief electric current through a tube containing an inert gas, usually xenon or krypton, and the result is a brilliant explosion of light. These two gases store vast amounts of electrons with complicated electronic structures giving them the quality of emitting light over a broad spectrum of wave lengths. This results in a bright white light when the electric current is passing through the gas.


The “avalanche” process is the name given to the phenomenon which causes the effect of “strobing.” Here, gas is ionized when an electric current passes through it. When the gas atoms meet the maximum point of avalanche, voltage collapses (avalanching) and electrons resume their normal state, causing brilliant light. Neon gases are used to determine rate of flashing frequency because it slows down the flashing rate of xenon, deemed too quick to be of any value to observation of an object in motion.

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High Voltage Required

The reaction of the current passing through the gas requires a tremendous amount of electrical energy, which calls for the use of a high voltage power supply to pump current to capacitors in the 200- to 600- volt range. Capacitors are joined through the flash tube filled with gas. The power supply sends a racing electrical charge through the connections causing a series of collisions that result in a turbulent arc of charged particles which then shoot through the tube and collide with the atoms of the gas, causing the bright light to burst forth. The light will disappear only when the current is terminated.

Strobes Have Many Uses

The strobe light has become a sort of universal symbol for “party” with its uses in discos and night clubs, intimating excitement and action inside. But, with the advent of stroboscopic flashlights and LED emergency lights, strobe lights also have uses in law enforcement. They are also used as safety equipment for SCUBA divers and bikers and continue to offer natural light for photographers.

Exercise extreme caution in all projects of do-it-yourself strobe building, since you will be working with powerful electrical currents.