Video: Understanding the Materials That Are Used in Making Wires

Electrical wires are often made of a copper core covered in a thin plastic coating. Which of the following are reasons why copper is chosen as the material for the core of the wire? [A] It is a good thermal conductor. [B] It is very cheap. [C] It is ductile. [D] It is very light. [E] It is a good electrical conductor.

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Video Transcript

Electrical wires are often made of a copper core covered in a thin plastic coating. Which of the following are reasons why copper is chosen as the material for the core of the wire? a) It is a good thermal conductor. b) It is very cheap. c) It is ductile. d) It is very light. E) It is a good electrical conductor.

So, this question is focusing on why exactly we choose copper as the material to make most of our electrical wiring from. We’ve been given five different potential reasons, and we need to work out which of these are actual reasons as to why we use copper. So, let’s go through them one by one.

Firstly, starting with a), it is a good thermal conductor. Now, a good thermal conductor easily allows heat to flow through it. And it’s true that copper is a pretty good thermal conductor. However, this is not a reason why we’d select copper. Because when we choose a wire material, we’re interested in how it conducts electricity, not so much in how it conducts heat. Strictly speaking then, good thermal conductivity is not a factor in our choice because the fact that it’s a good thermal conductor is not really relevant to electrical wires. And so, option a) is not an answer to our question.

Moving on to option b) then, it is very cheap. Now, copper is kind of cheap, but there are other substances that are much cheaper. For example, if we think about metals, then aluminium is cheaper than copper. And so, it’s not really true that copper is very cheap. By the way, the reason that we don’t use aluminium is because aluminium is not as good of an electrical conductor. Copper is much better at carrying an electrical current than aluminium is.

Anyway, moving on to option c) then, it is ductile. Now, this word here ductile refers to a material, in this case copper, that can be drawn out into a thin wire. In other words, any material that we can take from being, let’s say, a slab and apply pressure to it in certain directions to draw it out into a thin long piece of wire without breaking, of course, is known as a ductile material. And this is a very useful property of copper because if we want to make long thin wires, then we need a material that can be turned into long thin wires. And therefore, option c) is one of the answers that we’re looking for. The fact that copper is ductile is one of the reasons that we use it to make electrical wiring.

Moving on to option d) then, it is very light. Now, this is not really true, either. In fact, for the same amount of stuff, for the same amount of substance, if we compare copper and aluminium once again. So, say for example, we take two cubes of the exact same volume, one is copper, and the other is aluminium, then the aluminium cube is lighter. Or in other words, we can say that the density of aluminium, the amount of mass found in every unit of volume, is lower than the density of copper. And so, it’s not true that copper is very light.

Therefore, moving on to the final option, option e) says that copper is a good electrical conductor, which means that it’s good at carrying an electrical current. And this definitely is true. And it is a reason that we use copper in order to make electrical wires because we need something that can easily carry an electrical current. And therefore, at this point, we’ve gone through all of the options and found our answers. The reasons that we use copper to make electrical wires is because, firstly it is ductile, and secondly it’s a good electrical conductor.

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