Convection currents move tectonic plates when there is heat inside the mantle that is rising and falling. The radioactive decay in the core is responsible for the convection currents.
The convection currents in tectonic plates occur in the geosphere. The radioactive decay of elements is responsible for the heat deep within the earth, and this results in the creation of magma. Magma is a type of material that can be semi-fluid or completely fluid. It is very hot and when it starts to cool, it forms into igneous rock and lava. Convection currents also occur in wind in the atmosphere and in ocean currents in the hydrosphere.