The big picture
Light is reflected, or sent back, by a mirror. It bends when it goes through water or glass.
| Idea | Remember | Example |
|---|---|---|
| Law of reflection | i = r, from the normal | i = 35°, r = 35° |
| Plane mirror | Image as far behind as you are in front | A pencil 3 cm in front, its image 3 cm behind |
| Concave and convex mirrors | Convex: upright, smaller. Concave: depends on distance | A steel spoon |
| Parallel rays | Concave brings together. Convex spreads | Torch, side-view mirror |
| Refraction | Bends toward the normal into water | A ray at 40° in air bends to 29° in water |
| Under water | Looks higher than it is | A bent pencil |
| Lenses | Convex meets rays. Concave spreads them | A magnifying glass |
| Lens images | Convex: larger near, upside down far | Print under a lens |