As I inflate a balloon at a constant temperature does the pressure of gases inside it on the balloon increase? I know it's a dumb question but I am having a little misunderstanding with Boyle's Law.
Shouldn't pressure be inversely proportional with Volume , or this is meant for the pressure outside of gases outside the balloon,can you use another example for this relation .
 A: The general relation for an ideal gas is $$PV=nRT$$ where $P$ is the pressure, $V$ is the volume, $n$ is the number of moles of the gas particles, $R\approx 8.314 \mbox{ J/ mol}\cdot\mbox{K}$ is the gas constant and $T$ is the temperature in Kelvin.
As you inflate a balloon at constant temperature, $T$ remains constant while $n$ increases because you are adding gas with your lungs, and $V$ increases because it is inflating. Your question is what happens to the pressure $P$?
The answer is... the gas equations doesn't give you enough information to figure this out. Since $RT$ is constant you have $PV/n=\mbox{const.}$. But both $P$ and $V$ are allowed to vary so you need more information to answer this than just the gas law alone. 
However, you know that once you've blown into the balloon, the system will come to equilibrium, which means that forces on the balloon are balanced. You have pressure inside the balloon pushing out, and this must be balanced by the outside air pressure pushing in PLUS the force of the elastic which is also pushing in. The more the balloon is inflated, the more force the elastic will apply (think Hooke's law). Outside air pressure can be taken as constant. Therefore pressure will increase as you inflate the balloon, because the force from the elastic grows as the balloon is inflated. 
No need to invoke the gas law at all. In fact, the gas law can't save you here!
