Science
What are conductors and insulators?
Quick answer
A conductor lets electricity or heat pass through easily, like copper. An insulator blocks it, like plastic or rubber. Metals are good conductors; most non-metals are insulators.
In one sentence
Conductors let heat or electricity travel through them easily, and insulators stop or slow it down.
Explained
Some materials let energy flow, and some do not. This matters for safety, cooking and keeping warm.
Electrical conductors and insulators. Electricity flows through a conductor. Most metals are good conductors, with copper, silver, gold and aluminium among the best. The black part of a pencil, graphite, also conducts. Electricity cannot flow through an insulator, such as plastic, rubber, glass, dry wood and air.
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An electric cable is the perfect example of both. The inside is copper, a conductor, to carry the electricity. The outside is plastic, an insulator, to keep it from touching people. Plugs and switches have plastic cases for the same reason. You can test materials with a simple circuit using a battery, bulb and wires. Put the object in the gap. If the bulb lights, the material is a conductor. See electricity. Never test anything connected to mains electricity.
Heat conductors and insulators. Heat travels easily through some materials. A metal spoon left in a hot drink soon becomes too hot to hold, but a wooden or plastic spoon stays cool. Metal is a good thermal conductor, while wood and plastic are thermal insulators. That is why saucepans are metal, and their handles are plastic or wood.
Insulators keep things warm too. Wool, feathers and foam trap pockets of air, and air is a poor conductor of heat. A thick coat, a duvet, loft insulation and double-glazed windows all use this idea. A metal object in a cold room feels colder than a wooden one because it pulls heat from your hand faster, not because it is colder.
Pure water doesn't conduct well, but tap water has dissolved substances in it and does, which is why you should never use electrical devices near water. Learn about the group of materials that conduct best in metals.
Examples
| Material | Electrical | Heat |
|---|---|---|
| Copper | conductor | conductor |
| Plastic | insulator | insulator |
| Rubber | insulator | insulator |
| Wood | insulator | insulator |
| Air | insulator | insulator |
Common mistakes
- "Metal feels cold, so it is cold." It just moves heat away from your skin faster.
- "Water is always safe near electricity." Tap water conducts.
- "Insulators create heat." They only slow it down.
Quick quiz
Conductors and insulators
Check what you know with 4 quick questions.
Question 1 of 4
Which material is a good electrical conductor?
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Related topics
Electricity
Electricity is the flow of tiny charged particles called electrons through a material. It powers lights, phones and machines, and it can come from batteries or the mains supply.
Electric circuits
An electric circuit is a complete loop that electricity flows around. A simple circuit has a battery, wires and a component like a bulb. If the loop is broken, the electricity stops.
Metals
Metals are shiny, strong materials that conduct heat and electricity and can be hammered or stretched into shape. Iron, copper, gold and aluminium are metals.
Adaptation
An adaptation is a feature or behaviour that helps a living thing survive where it lives. A polar bear's thick fur and a cactus's spines are adaptations.
Amphibians
Amphibians are cold-blooded animals with thin, moist skin that live part of their lives in water and part on land. Frogs, toads, newts and salamanders are amphibians.
Birds
Birds are warm-blooded animals with feathers, wings and a beak. They lay hard-shelled eggs, and most can fly. Penguins, ostriches and parrots are all birds.