This excess heat will raise the temperature of the power supply to some equilibrium temperature. The equilibrium temperature depends on several factors such as the amount of power turned into heat, temperature of the environment and the surface area. The power dissipated as heat is determined by the circuit topology and defined by the power supply specifications. Temperature of the environment is defined by the specific application. The one element which the power supply user can easily manipulate is the surface area.
Heat sinks increase the effective surface area of the power supply.
These three methods are usually analyzed and described separately. However, heat removal is always a combination of these methods. Conduction is very important in electronic equipment and is the only mode of heat transfer occurring in solids. Conduction is transmission of heat by transfer of kinetic energy from one molecule to another and it can occur in a solid, liquid, or gas. In liquids, conduction and convection can occur simultaneously, while all three modes of heat transfer occur simultaneously in a gaseous environment.