Falling charges: The particle drop tower used in the experiment. (Courtesy: N Mujica) Static electricity is an everyday phenomenon, but it is not well understood. Researchers at the University of Chile have now added another piece to the puzzle by conducting experiments on the charge distributions of free-falling particles. They found that same-sized particles within the sample had the same range of surface charge densities, suggesting that particle size plays a major role in static electricity. Their work could improve our understanding of how charge behaves on insulating surfaces, with implications in areas ranging from planet formation to lightning generation in volcanic plumes and clogging in industrial processes. Static electricity is also known as contact electrification because it occurs when charge transfers from one object to another as the two touch each other. (Think of rubbing a balloon on someone’s head to make their hair stand on end).…