Choose the best answers for the case below:
One evening, Sia noticed sparks coming from the wire of her table lamp. Her father saw that the plastic covering of the wire was torn, exposing the copper wire inside. He immediately switched off the power supply and explained that damaged wires can be dangerous. He told her that electrical wires are always covered with plastic or rubber for safety.
1. The copper wire inside the lamp is used because copper is a
2. The plastic covering of the wire is used to
3. Sparks were produced because
4. Damaged wires are dangerous because they