Why are electrical plugs made of plastics? (A) Plastics are stronger than other materials (B) Plastics is a good electrical conductor (C) Plastics protect people from electricity (D) Only plastic can be made into the right shape of a plug
Hint: Electrical plugs are used in the environment where there is a chance of suffering electrical shocks. Shocks are experienced when current flows through our bodies. So, we can use insulators to cover the surfaces of the electrical systems that come in direct contact with our bodies.
Complete step by step answer: Plastics: Plastics have been used for various purposes. The clothes we wear, places where we live, vehicles we travel in and toys kids play with. Most of the things we use contain plastics. This creates a clear picture in our mind that it can be molded into various shapes and sizes. They are not stronger than other materials. The gap between the valence and the conduction band for electrons in a molecule of plastic is much-much higher than that in metals and semiconductors. This means that the electrons cannot move so freely. Hence plastic is a poor conductor of electricity. Being a poor conductor, they prevent people from conducting electricity. There are other materials which can be molded into the shape of a plug.
Option C is correct.
Note: The question can be solved by using the elimination method as well: Plastics are weak materials as compared to metals. So, option A is incorrect From the question itself we can see that if wiring is not covered with plastics then we could get electrical shocks. This shows that plastics don’t allow electricity to pass through it. Therefore, option B cannot be the correct solution. Other synthetic fibers can also be used to make plugs. This reflects that D is the wrong option. Hence only the C option seems appropriate.