Emergency vehicles use a second type of strobe. These lights have an internal mechanism that spins one or two bright lights around inside a case, which is usually tinted blue or red. As the lights spin, they shine outward through openings in a housing inside the case, creating a flashing effect. However, because the effect is created by spinning rather than powering on and off, it is technically a strobe.

Visual Effects

Flashing lights can draw attention, such as flashing lights on signs or traffic signals, or to create a lively atmosphere due to constantly changing visuals, such as you might find in Las Vegas casinos. The visual effect commonly known as a strobe effect requires absolute darkness when the light is off or covered. The regular intervals of dark and light allow you to see images as distinct events instead of your brain interpreting them as fluid motion. This creates the stop-motion effect for which strobe lights are known.

Dangers

Some forms of epilepsy make people sensitive to flashing light, so both flashes and strobes can trigger epileptic fits. This is why you may see warning signs outside nightclubs or theatrical performances that use strobe lights. Commercially available strobe lights usually flash no more than 10 to 12 times per second, which minimizes the risk of triggering seizures. However, lights that are flashed manually can be set to turn on and off at higher speeds, increasing seizure risk. Slower flashing and strobing speeds can still trigger epileptic fits in prone individuals, so use care when using any flashing or strobing light.