insulator

Everyday

1. An insulator is a material that does not let heat pass through it easily, like wool, plastic foam or air. tree →
2. An insulator is also a material that does not let electricity flow through it, like plastic, rubber, wood or glass. tree →

In the lessons

In science lessons, children test materials as good or poor insulators: thermal insulators keep heat in (hot drinks in a flask, a woolly hat, house insulation) or keep heat out (a cool box for ice). Electrical insulators keep us safe: plastic covers on wires and plugs stop electricity reaching our hands. The opposite is a conductor (metals conduct both heat and electricity well). Phrases: «a good insulator», «a poor insulator», «thermal insulator», «electrical insulator».

Examples

• Plastic is a good electrical insulator. tree →
• The plastic coating on the wire is an insulator. tree →
• Wool is a good insulator, so it keeps us warm. tree →
• We tested which material was the best insulator for keeping ice from melting. tree →
• Metal is a conductor, not an insulator. tree →
• Air trapped in feathers is a great insulator. tree →
• Polar bears' thick fur and fat are insulators. tree →
• Wooden spoon handles are insulators, so they don't get hot. tree →

Note

Countable: «an insulator» (vowel, so «an»). Opposite: «conductor». Verb: «insulate»; noun: «insulation». Myth: a coat does not make heat; it is an insulator that keeps your own body heat in. Water with salts in it can conduct electricity, so wet insulators may be unsafe.