| Term | Definition |
| Electromagnetic Wave | A transverse wave that transfers electric and magnetic energy |
| Electromagnetic Radiation | The energy transfered by electromagnetic waves |
| Photon | A "packet" of light energy |
| Radio Waves | The electromagnetic waves with the longest wavelength |
| Gamma Rays | The electromagnetic waves with the shortest wavelength |
| Thermogram | An image that shows different temperature regions using infrared rays |
| Luminous | An object that gives off its own light |
| Illuminated | An object that you see by reflected light |
| Transparent | A material that transmits most of the light that hits it |
| Translucent | A material that scatters light as it passes through |
| Opaque | A material that reflects or absorbs all of the light that hits it |
| Pigments | Colored substances used to color other materials |
| Concave Mirror | A mirror that curves in like a bowl |
| Convex Lens | A lens that is thicker in the center than the edges |
| Retina | The layer of cells inside the eye that consists of rods and cones |
| Pupil | The opening through which light enters the eye-it can expand and contract |