Lesson 1 of 14
Shine, and the sound it makes
Show on a big screenTap a bell. Tap a wooden bench. Which one keeps ringing?
Step 1 of 3
- A clean steel spoon under a light. A bell, not yet struck.
- Light bounces off the spoon. This is lustre.
- The bell is struck. It rings on. This is sonorous.
The bell keeps ringing after a tap. The bench does not.
Two tests, two words
- Lustre — a clean surface bounces light back.
- Sonorous — struck once, it rings on for a while.
The rule
Shine and ringing are two tests. One pass is not enough.
Most metals pass both tests. Most non-metals pass neither. A wooden bench gives a dull thud, with no ringing.
Watch out!
A glass marble shines too, and it is not a metal. A magnet does not tell metal from non-metal either. Copper is a metal, yet a magnet does not pull it.
Now try it. Pick a thing. Shine it, then tap it. Is it a metal?
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Try the lab to finish this lesson.