Air pressure, defined by the popular perception of the meaning is the amount of air in your car tires.  A meteorologist would be inclined to refer to it as atmospheric pressure, which is measured with a barometer.  However, the physicist might say that the air molecules are repelling each other at a static rate until an outside force acts on them.  All of these groups are correct. In short, air is a soup of various molecules of gas, liquid, and … Continue reading Sound – The early wireless communication protocol