Which things gleam?
Metals shine. That shine is called lustre.
In the ironsmith's shop
At Sudarshan uncle's iron shop there are tawas, buckets and axes made of iron. The handles are wood. The furnace burns coal.
Shine a torch on a clean piece of iron and on a lump of coal. What do you think you will see?
What this lesson covers
The idea
Metals such as copper, aluminium and iron are lustrous and hard, and the lustre shown by metals is called metallic lustre; coal, sulfur and wood are non-lustrous and not as hard.
In the ironsmith's shop
At Sudarshan uncle's iron shop there are tawas, buckets and axes made of iron. The handles are wood. The furnace burns coal.
Shine a torch on a clean piece of iron and on a lump of coal. What do you think you will see?
- Both gleam
- Only the iron gleams
- Only the coal gleams
Shine a light
Shine the light on each material. First guess, then watch what the light does.
Metallic lustre
Metals such as copper, aluminium and iron are lustrous and hard. The lustre shown by metals is called metallic lustre. Coal, sulfur and wood are non-lustrous and not as hard as metals.
Objects made of copper, aluminium and iron are called metals.
- Material | In the light
- Copper, aluminium, iron | gleam (lustrous)
- Coal, sulfur, wood | stay dull (non-lustrous)
Notes
Metals (copper, aluminium, iron) are lustrous and hard. Their shine is called metallic lustre. Coal, sulfur and wood are dull and not as hard.
Check yourself
The shine shown by metals is called...
Which of these gleams in the light?
Which pair is lustrous and hard?
In the ironsmith's shop, which of these would gleam if it were clean and held in the light?
- metallic dullness. Dullness means no shine. It is the opposite.
- metallic lustre — correct. Yes! Metals show metallic lustre.
- metal paint. It is not paint. It is the natural shine of the metal.
- A lump of coal. Coal is non-lustrous. It stays dull.
- A clean piece of copper — correct. Yes! Copper is a lustrous metal.
- A block of wood. Wood is non-lustrous. It stays dull.
- Coal and sulfur. Both are non-lustrous and not as hard as metals.
- Sulfur and wood. Both are dull and not as hard as metals.
- Copper and aluminium — correct. Yes! Both are metals: lustrous and hard.
- The wooden handle. Wood is non-lustrous.
- The coal in the furnace. Coal is non-lustrous.
- The iron tawa — correct. Yes! Iron is a metal, so it shows metallic lustre.