Q1.
Is water transparent? Can it be made opaque?
Answer
Yes, clean water is transparent — the book lists water along with glass, air and cellophane paper as an example of a transparent material. Drop a coin into a glass of clean water and you can read the year on it.
And yes, water can be made opaque — by mixing something into it.
| What you add to water | What it becomes |
|---|---|
| Nothing (clean water) | Transparent — the coin is seen clearly |
| A little chalk powder or fine mud | Translucent — the coin is a blur |
| Plenty of mud, milk or ink | Opaque — the coin cannot be seen at all |
Note that adding sugar or salt does not make water opaque. They dissolve completely, so the water stays transparent — only its taste changes.
Why it happens: tiny insoluble particles floating in the water block and scatter the light travelling through it. The more particles, the less light gets straight through — clear water becomes hazy, then completely opaque. A dissolved material leaves no such particles.
Check it yourself: Take three glasses of water. Put a coin in each. Add a spoon of sugar to the first, a spoon of chalk powder to the second, and a spoon of milk to the third. Only the first coin stays clearly visible.