Insulator vs Conductor:
In order to understand why plastic wire is an insulator, we need to first understand the difference between an insulator and a conductor.

- An Insulator: An insulator is a material that does not allow the flow of electric current through it easily. It has a high electrical resistance. Examples of insulators include rubber, glass, and plastic.

- A Conductor: A conductor is a material that allows the flow of electric current through it easily. It has a low electrical resistance. Examples of conductors include metals such as copper and aluminum.

Why is Plastic Wire an Insulator?
Plastic wire is made of a material called PVC (Polyvinyl Chloride), which is an excellent insulator. There are several reasons why plastic wire is an insulator:

1. Electrical Resistance: PVC has a high electrical resistance. This means that it does not allow electric current to flow through it easily. When an electric current passes through a material with high resistance, it encounters a lot of opposition and loses energy in the form of heat. This property makes PVC suitable for insulating wires, as it prevents the flow of excessive current and reduces the risk of overheating or short circuits.

2. Non-conductive Nature: PVC is a non-conductive material, which means it does not contain free electrons that can move easily and carry electric charge. In contrast, conductors like metals have free electrons that can move freely and facilitate the flow of electric current.

3. Dielectric Properties: PVC has good dielectric properties, which means it can store electrical energy without conducting current. This property makes PVC suitable for insulating the wires in electrical equipment and appliances, as it prevents the leakage of electrical energy and ensures safety.

4. Thermal Insulation: PVC is also a good thermal insulator, which means it prevents the transfer of heat. This property is beneficial in electrical wiring, as it helps to protect the wires from damage due to excessive heat generated by the flow of current.

In Conclusion:
Plastic wire is an insulator because it is made of PVC, which has high electrical resistance, non-conductive nature, good dielectric properties, and thermal insulation. These properties make it suitable for insulating wires and ensuring the safe transmission of electrical current.