Boyle's Law Explained
Boyle's Law was founded by Robert Boyle (1627-1691), who was one of the great intellectuals of the century. Boyle's Law in a nutshell states that for a gas, when the pressure is increased, the volume will also decrease. Conversely, if the volume is increased, then the pressure will decrease. Throughout this all, the temperature T is held constant. The volume V is proportional to the pressure P as related in the following equation:
1) V ˜ 1/P
2) P ˜ 1/V
where P is the absolute pressure. Boyle's Law is normally written as:
3) PV = Constant
as well as:
4) P1V1 = P2V2
where P1 and V1 are the initial pressure and volume of the gas, and P2 and V2 are its final values.
So, for example, if the pressure on a gas is doubled, the volume decreases by one half. You can easily see this from equation 2 if you double the pressure and then solve for P. Figure 2 gives a graphical depiction of this relation.
These results apply for systems where an equilibrium state has been reached, the gas is not too dense, and P is around atmospheric pressure. Because real gases only approximate these conditions, this law is considered to apply to what is known as an ideal gas. Its predictions are accurate enough however, that any gas or gas mixture under proper conditions can meet it. Well-known examples include methane, oxygen, air, and helium.
Now that you know the formula, in part two we will explain the connection between this law and diving.
Carl Brasher from Chasingthefrog.com
PV Diagram from NASA Glenn Research Center