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.
Matter is anything that takes up space and has mass or weight. Matter exists in three forms or states - solid, liquid and gas. All matter is made up of molecules, the smallest part of a substance that can still be that substance. Molecules in gases are far apart and they move around more. Gases have no definite size or shape. Liquids' molecules are closer together than those of gases but less so than those of solids.