Task: Text Categorization
Input (English): Silica aerogels are frequently used in devices for measuring this phenomenon, and one such device is called the threshold detector, while another device used to measure it is called a ring imaging detector. The governing equation can be derived by using Poynting's theorem and applying the Fourier transform to determine the energy loss at infinite distance. A periodic grating can give rise to a version of this effect named after Smith and Purcell, while the Frank-Tamm equation governs this phenomenon, which travels at an angle whose cosine is inversely proportional to the index of refraction and the object's speed. For 10 points, name this effect in which a charged particle moves through a medium faster than the speed of light in that medium, giving off radiation.
Output (English): Science