One case of a particle’s movement. It begins as the red point, resting on the surface of the hand (black wavy line). It follows the blue path, escaping the hand and then moving freely through the hand-washing fluid. Credit: Paul Hammond
One case of a particle’s movement. It begins as the red point, resting on the surface of the hand (black wavy line). It follows the blue path, escaping the hand and then moving freely through the hand-washing fluid.