Which is evidence that supports the dynamo theory

The earth's core is dominantly composed of nickel and iron. Outer core is liquid and inner core is solid.

            The liquid present in the outer core moves continuously over the much denser solid inner core, acting as electrically conductive medium. Due to this a magnetic field is produced, which develops a magnetosphere that obstructs the incoming solar radiations from the sun.

Thus the outer liquid core helps us in understanding the dynamo theory.