IG Phy –  Transfer of Thermal Energy (I)

Materials that allow thermal energy to transfer quickly through them are called thermal conductors.

Wood and plastic are examples of good thermal conductors.

Metals are good thermal conductors because they contain free, or delocalized, electrons that transfer energy rapidly.

Conduction can occur in a vacuum where there are no particles.

In metals, the thermal energy is transferred by both the vibrations of atoms and the movement of free electrons.

Liquids are generally good conductors of thermal energy.

Convection is the main method of thermal transfer in solids.

Convection occurs in fluids because their particles can move freely.

In a convection current, warmer fluid rises and cooler fluid sinks.

The movement of free electrons makes metals act as good thermal conductors.

Convection currents can be demonstrated using potassium permanganate crystals in water.

Insulators prevent thermal energy transfer by restricting the movement of fluids.

Metal handlebars on a bike feel colder than plastic grips because metal is a good thermal conductor.

Gases are poor thermal conductors because their particles are far apart.

Free electrons in a metal gain kinetic energy at the hot end and transfer this energy by colliding with atoms at the cooler end.

Metals are poor conductors of thermal energy because they have fewer free electrons compared to liquids and gases.