• 9-12: 4B/H8. The earth has many natural resources of great importance to human life. Some are readily renewable, some are renewable only at great cost, and some are not renewable at all.

• 9-12: 4D/H1. Atoms are made of a positively charged nucleus surrounded by negatively charged electrons. The nucleus is a tiny fraction of the volume of an atom but makes up almost all of its mass. The nucleus is composed of protons and neutrons which have roughly the same mass but differ in that protons are positively charged while neutrons have no electric charge.
• 9-12: 4D/H9b. Some atoms and molecules are highly effective in encouraging the interaction of others.

• 9-12: 4E/H7. Thermal energy in a system is associated with the disordered motions of its atoms or molecules. Gravitational energy is associated with the separation of mutually attracting masses. Electrical potential energy is associated with the separation of mutually attracting or repelling charges.

• 6-8: 4G/M4. Electrical circuits require a complete loop through which an electrical current can pass.
• 9-12: 4G/H4ab. In many conducting materials, such as metals, some of the electrons are not firmly held by the nuclei of the atoms that make up the material. In these materials, applied electric forces can cause the electrons to move through the material, producing an electric current. In insulating materials, such as glass, the electrons are held more firmly, making it nearly impossible to produce an electric current in those materials.

How does a solar panel convert sunlight into electrical current? This interactive animation takes a close-up look at each layer of a basic photovoltaic cell to show how electrons are energized when sunlight strikes the cell.

• Physics First Renewable Energy Sources Unit
• Conceptual Physics Renewable Energy Sources Unit
• Algebra-Based Physics Renewable Energy Sources Unit
• AP/Calculus-Based Physics Renewable Energy Sources Unit