Pressure and temperature are directly proportional when the volume and amount of gas remain constant. This relationship is known as Charles's Law, which states that the volume of a gas is directly proportional to its absolute temperature when pressure and amount of gas are held constant.
Mathematically, it can be expressed as:
P ∝ T
Where P represents pressure and T represents temperature.
According to Charles's Law, as the temperature of a gas increases, its pressure will also increase, and vice versa, as long as other factors remain constant.