CRITICAL POINT, in physics, the point above or below which certain physical changes will not occur. In the study of change of state (see HEAT and THERMODYNAMICS) the properties of the substance at this point are called its critical constants. In mechanics, the smallest angle which an inclined plane must make with the horizontal in order that a body resting on it should slide is called the critical angle. (See FRICTION.) In an oscillat ing system the critical damping is the minimum amount of damp ing that will cause the value of its potential energy to fall to zero without further oscillation. (See VISCOSITY; CONDENSER [ELEC TRICAL] and GALVANOMETER.) There are numerous other instances of this application of the word critical in the sense of "limit