German chemist who applied the principles of thermodynamics to the electric cell. He constructed an equation, known as the Nernst Equation, which related the voltage of a cell to its properties. Independently of Thomson, he explained why compounds ionize easily in water. The explanation, called the Nernst-Thomson rule, holds that it is difficult for charged ions to attract each other through insulating water molecules, so they dissociate. Nernst was awarded the 1920 Nobel Prize in chemistry for his discovery of the Third Law of Thermodynamics , which states that entropy approaches a minimum (which can be arbitrarily set to zero) as temperature approaches absolute zero. He also built a ceramic lamp.