Energy flows in the core also responsible for another of the planet’s unique features: a strong magnetic field. Scientists believe that the earth has had a magnetic field for at least 3.5 billion years. The basic mechanism of magnetic field generation is a dynamo process, in which the kinetic energy of convective motion in the Earth’s liquid core is converted into magnetic energy. The velocity of this fluid movement is on the order of 10 kilometers per year. The rotation of the earth couples this motion into a circulation that generates electric currents, and the electric currents in turn generate a magnetic field according to classical electromagnetic theory. Since this process operates without an external energy source, the geodynamo is said to be self-sustaining. Without that regenerative process the electric currents and the associated magnetic field would dissipate in about 15,000 years. Sources Department of Geological Sciences, San Diego State University, The earth's internal energy and internal structure, Accessed 27 June 2007. Lawrence Berkeley National Laboratory, The truth about Earth's core?, Accessed 27 June 2007. Pennsylvania State University, Probing Question: What heats the earth's core?, Accessed 27 June 2007. ScienceDaily, Discovery Of Earth's Inner, Innermost Core Confirmed, Accessed 21 August 2008.
My question is that the earths magnetic field is caused due to its mass or its core