Thermal Energy Transfer~Explora Science

This week's Explora Science Club class entailed students using hands-on, tabletop experiments to understand how molecules transfer heat through conduction, convection and radiation.
In thermal science, heat transfer is the passage of thermal energy from a hot to a cold body. When an object or fluid, is at a different temperature than its surroundings or another body, transfer of thermal energy, occurs in such a way that the body and the surroundings reach thermal 'equilibrium'. Heat transfer always occurs from a hot body to a cold one, in relation to thermodynamics. Transfer of thermal energy occurs mainly through 'conduction', 'convection' or 'radiation'. Heat transfer can never be stopped; it can only be slowed.

"Conduction" relates to how heat is transferred when adjacent atoms vibrate against one another, or as electrons move from atom to atom. Conduction occurs mainly in solids, where atoms are in constant contact. In liquids and gases, the particles are further apart, giving a lower chance of particles colliding and passing on thermal energy.
Metals are the best conductors of thermal energy. This is due to the way that metals are chemically bonded. In this experiment, the students fire-tested steel, copper and ceramic to see which one was best at conducting heat, by seeing how quickly the wax-attached coins melted and fell off each one.
Jenna brought Scooby to learn about Thermal Energy.
Conlin invited the students to experience "radiation", which is basically how all objects transfer heat through electromagnetic radiation.Hot or cold, all objects radiate heat. "Shiny" materials typically reflect radiant heat, just as they reflect visible light; dark materials typically absorb heat, just as they absorb visible light.
"Convection" combines conduction with physical movement of the hot particles to cooler areas. In this experiment, the students watched the direction of smoke rise between two sources: one hot water, and one ice. I loved the way the girls looked so intent while peeking over the table.


Another example of "Convection": In this experiment showing 'Natural Convection', two vials, one filled with red hot water and one filled with blue cold water were gently placed into a bowl of room temperature water. Immediately the red water rose to the top, while the blue water stayed within it's bottle. This 'Natural Convection' experiment showed how fluid surrounding a heat source receives heat, becomes less dense and rises. The surrounding, cooler fluid then moves to replace it. This cooler fluid is then heated and the process continues, forming a "convection current". The primary driving forces for natural convection are buoyancy and gravity. Fascinating stuff!