What causes volcanoes to occur at convergent boundaries

If two tectonic plates collide, they form a convergent plate boundary. Usually, one of the converging plates will move beneath the other, a process known as subduction. ... The new magma (molten rock) rises and may erupt violently to form volcanoes, often building arcs of islands along the convergent boundary.

explanation: it gains negative electrons, therefore becoming negatively charged. as charge cannot be created, nor destroyed, only transferred, this leaves the wool positive. now that they have opposite charges, the two items attract.