Describe how the wool and the shiny layer contribute to keeping the house warmer, and how metal roofs absorb and transfer heat better into and away from the house than any other materials. Describe how metals transfer heat.

Infrared radiation is a form of electromagnetic radiation.

• It is invisible to the human eye.
• It can travel through a vacuum.
• It transfers energy as heat.
• It travels at the speed of light.

Two properties of infrared radiation are:

1. It is invisible.
2. It transfers heat energy.

Wool is a good insulator because it traps air within its fibers. Trapped air is a poor conductor of heat and prevents heat loss by convection.

A shiny layer is a poor emitter and a good reflector of thermal radiation. It reflects infrared radiation back into the house, reducing heat loss by radiation.

Metals transfer heat primarily through conduction. This occurs due to two main mechanisms:

• Free electrons: Metals have delocalized electrons that can move freely. When heated, these electrons gain kinetic energy and collide with other electrons and metal ions, transferring energy rapidly throughout the material.
• Vibrating lattice ions: The metal ions in the lattice vibrate more vigorously when heated, transferring energy to adjacent ions. The free electrons are the more significant contributor to the high thermal conductivity of metals.

Metals transfer heat through the vibration of their lattice ions and the movement of free electrons. When heated, electrons gain kinetic energy and move faster, colliding with other electrons and ions, transferring energy efficiently.