Charles' law states that at a fixed pressure a quantity of gas has a volume directly proportional to its temperature. This means that gas kept at a constant pressure increases or decreases in volume as temperature does the same. As temperature rises, the gas molecules or particles are excited and push at surfaces with more force, creating a greater volume.
Charles' law is also known as the law of volumes, with an equation indicating that volume divided by temperature equals the constant. This equation is easier to determine if a gas is maintained at a constant pressure and the constant changes only by the increase or decrease in temperature.
This gas law was discovered in the 1780s by a scientist named Jacques Charles who formulated the original law that was published decades later. This law is still commonly taught today and led to discoveries such as liquefied gases and the behavior of gas as it nears a temperature of absolute zero. Charles' law is related to the kinetic theory of gases, in which gases are large numbers of small particles that collide with each other as well as the walls of their container at a constant rate. Temperature adds energy to these particles, increasing the rate at which they move and collide with other particles.