The principle that, for relatively low pressures, the pressure of an ideal gas kept at constant temperature varies inversely with the volume of the gas.
Mathematically, Boyle's law can be stated as
PV = k
where P is the pressure of the gas, V is the volume of the gas, and k is a constant.
The equation states that product of pressure and volume is a constant for a given mass of confined gas as long as the temperature is constant. For comparing the same substance under two different sets of condition, the law can be usefully expressed as
P1v1 = p2v2
The equation shows that, as volume increases, the pressure of the gas decreases in proportion. Similarly, as volume decreases, the pressure of the gas increases. The law was named after chemist and physicist Robert Boyle, who published the original law in 1662.
The law itself can be stated as follows:
For a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional.
Or Boyle's law is a gas law, stating that the pressure and volume of a gas have an inverse relationship, when temperature is held constant. If volume increases, then pressure decreases and vice versa, when temperature is held constant.
Therefore, when the volume is halved, the pressure is doubled; and if the volume is doubled, the pressure is halved.