Why are volcanoes commonly found at the edges of earth's moving plates?

Volcanoes are commonly found at the edges of Earth's moving tectonic plates or because the magma in between the plates is forced up, creating a volcano. The area between the plates is weak, making it easier for the magma to push through and volcanoes to form. 

Answer feldspar,quartz,mica and amphibole;

There is a great difference between the windward and leeward side of a mountain. windward and leeward sides are opposites.