| A | B |
|---|
| Light ray | Wave of light represented as a straight line |
| Plane mirror | A flat, smooth mirror |
| Concave mirror | A mirror whose surface curves inward (like front of spoon) |
| Convex mirror | A mirror that curves outward, like the back of a spoon |
| Virtual image | An image that your brain perceives even through no light rays pass through the location of the image |
| Optical axis | An imaginary straight line drawn perpendicular to the surface of the mirror at its center |
| Focal point | The point on the optical axis where formerly parallel light rays reflect and converge (for a concave mirror) |
| Focal length | The distance from the center of a mirror to the focal point |
| Real image | An image that is formed when light rays converge to form the image |
| Lens | A transparent material with at least one curved surface that causes light to bend |
| Convex lens | Lens that is thicker at the middle than at the edges |
| Concave lens | Lens that is thinner at the middle and thicker at the edges |
| Cornea | Clear covering on the eye |
| Eye lens | Transparent tissue inside eyeball that focusses light on retina |
| Retina | Layer of tissue that lines the back of eye, transforms light into electrical signals to send to the brain |
| Nearsightedness | Condition where only nearby objects can be seen clearly |
| Farsightedness | Condition where only far away objects can be seen clearly |
| Astigmatism | When the surface of the cornea has an uneven curve |
| Refracting telescope | Uses lenses to gather light from distance objects |
| Reflecting telescope | Uses mirrors and lenses to collect and focus light from distant objects |
| Compound microscope | A device that uses two convex lenses to magnify small, close objects |
