Completar Frases Fill in the blanksVersión en línea Electricity por Henar Aguado 1 insulators electrical copper glass insulators conductors good metal Some materials let electricity pass through them easily . These materials are known as electrical . Many metals , such as , iron and steel , are electrical conductors . That is why the parts of electrical objects that need to let electricity pass through are always made of . Some materials do not allow electricity to pass through them . These materials are known as electrical . Plastic , wood , and rubber are good electrical . That is why they are used to cover materials that carry electricity . The plastic covering that surrounds wires is an electrical insulator . It stops you from getting an shock .