Answer :
Final answer:
Heat transfer in the Earth's outer core occurs mainly by convection due to the movement of molten materials. Conduction is less significant in the outer core, while radiation is a key mechanism at the Earth's surface, termed insolation. So the correct option is C.
Explanation:
In the Earth's outer core, heat transfer occurs mainly by convection. This is because the outer core is composed of molten iron and nickel which, being fluid, enables the transfer of heat via the movement of the fluid itself. As the hot material rises and the cooler material sinks, convection currents are set up, contributing significantly to the transfer of heat within this layer.
Conduction, on the other hand, is the transfer of heat through direct contact between materials. It is less significant in the outer core due to the fluid nature of the molten iron and nickel, which allows for more efficient convection processes.
Radiation is a method of heat transfer that involves the emission of energy as electromagnetic waves and does not require a medium to travel through. This type of heat transfer is not the primary mode at play in the Earth's outer core. However, it is a crucial mechanism at the surface of the Earth, where heat from the Sun reaches the planet through radiation, also known as insolation.
