Answer:
Thermal energy can be transferred by conduction, convection or radiation
Step-by-step explanation:
Thermal energy is the energy that flows from one point to another due to temperature differences between the points. There are three ways by which thermal energy is transferred which are conduction, convection and radiation.
In conduction, thermal energy is transferred in solids usually metals due to their good heat conductivity. An example is seen in the use of metals for preparing meals. Heat (or thermal energy) is transferred from the fire to the metal to the food.
Convection occurs in fluids (liquids and gases). It usually occurs in a cyclic manner. For example in heating water, thermal energy is gained by water molecules closest to the heat source (at the base of the container) and become lighter causing them to rise to the top. The molecules at the top become denser and sink to the bottom whereby they gain energy and rise in a similar manner. This repeated phenomenon occurs in a cyclic form whereby there's displacement of colder and denser molecules by warmer and lighter molecules. Another example is the occurrence of sea and land breezes.
Radiation occurs without the need of any material medium unlike conduction and convection. In radiation, heat is directly transferred from one point to the other without being transferred by molecules. This is seen in how thermal energy from the sun reaches the earth. In other words, heat is transferred in a vacuum