Planck constant, named H, is a physical constant that describes the quantum size. It plays an important role in quantum mechanics. When Max Planck studied the law of thermal radiation of objects in 1900, he found that as long as the emission and absorption of electromagnetic waves were not continuous, but one after another, the calculated results could be consistent with the experimental results. Such an energy is called an energy quantum, each energy quantum is equal to hv, V is the frequency of radiated electromagnetic waves, and H is a constant called Planck constant.