Question

What causes the convection currents in the mantle?

Answer 1

Heat  from the core and the mantle itself causes convention currents in the mantle.

Answer 2

                             CAUSE OF CONVECTION CURRENT

                    According to the general term, the lighter material rises whereas the dense material sinks. This relationship briefing is called the conventional current. The convention is defined as the process by which heat energy is transferred by movement of a heated liquid.

                   This heating effect is setup by the local radiation. The earth core part is called as the mantle. The convention current causes the heating effect in the mantle. The heating effect causing the mantle of the earth to look like a fire ball.