How Fuel Cells Work. Polymer Electrolyte Membrane (PEM) fuel cells used in automobilesâalso called Proton Exchange Membrane fuel cellsâuse hydrogen fuel and oxygen from the air to produce electricity. The diagram and animation below show how a PEM fuel cell works.
Sound is what happens when you transmit vibrations of energy through that matter. Sound is made up of wave vibrations. When you talk aloud, the motion of your vocal cords causes the air to vibrate. Air is made up of molecules, and as those air molecules vibrate, they hit each other.
What is the scientific definition of sound? A: Sound is a mechanical wave resulting from the back and forth vibration of the particles of the medium through which the wave is moving. The compressions and rarefactions of sound waves move parallel to the direction of wave propagation, making sound a longitudinal wave. Continue Reading.