Pressure Law
Pressure law states that for a fixed mass of gas, the pressure of the gas is directly proportional to the absolute temperature of the gas provided the volume of the gas is kept constant.
![](http://spmphysics.blog.onlinetuition.com.my/wp-content/uploads/sites/4/2020/02/Heat-formula8.svg)
Formula:
![](http://spmphysics.blog.onlinetuition.com.my/wp-content/uploads/sites/4/2020/02/gas-law-19-e1581358770787.png)
Explanation
- The kinetic energy of gas molecules increases with temperature.
- The air molecules collide with the wall of the container at higher velocity and frequency.
- The pressure in the gas increases, causing an increase in volume.
Graph
- In the graphs above, the first graph shows that P is directly proportional to the absolute temperature.
- The second graph shows that, if the temperature is in °C, the graph does not pass through the origin.
- The third and the forth graphs shows that P/T is always constant for all value of P and T.