Question

Explain why:
a) An expanded polystyrene is a good insulator.
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Answer 1

Answer:

Polystyrene and plastic foam are both used as insulators as they have small air bubbles trapped inside them. This makes them very good insulators because heat energy can't flow through them.

OR

Expanded polystyrene is quite good at not transmitting sound, but that's because it reflects a lot back. So quite good for soundproofing and thermal insulation (if enclosed in suitable fire-resistant material), but not good for acoustic treatment in a studio.