Which things bounce light back?
When light hits an object, three things can happen. It can bounce off, which is reflection. It can be taken in, which is absorption. Or it can pass through. Shiny, smooth things such as a mirror or kitchen foil reflect a lot of light. Dull, dark or rough things such as black cloth absorb most of it and reflect little. Clear glass and clear plastic are transparent: light passes through and we see through them. Wood, metal and thick cloth are opaque: they do not let light pass. To test this, a grown-up helps in a dim room. Lay each material on a table, shine a torch on it from the side, and look at the patch of light it makes on a white wall or card nearby. Predict first, then record how bright the patch is. Keep the torch distance and angle the same for each material. Never shine the torch or a reflected beam at anyone’s face.
| Material | Prediction | Patch on the wall |
|---|---|---|
| foil | bright | bright |
| white paper | dim | faint |
| black cloth | none | almost none |
| clear plastic | goes through | light goes through |
Reflect, absorb, pass. With a grown-up, in a dim room, test five things: a mirror, kitchen foil, white paper, black cloth, clear plastic. Predict for each one: bright patch, faint patch or no patch. Shine the torch from the same distance and angle. Write your results in a table. What do the best reflectors have in common? (Shiny and smooth.) Never aim the torch or a reflection at faces.