Electric Charges and Fields

Conductors and Insulators

How many of you have experienced a feeling of electric shock while opening the window of your car or coming in contact with wires in wet condition? Isn’t that a bit scary? But, why is that? Why don’t you get similar experiences with wooden materials? It is because they are insulators.

The reason you get a shock is that there occurs a flow of electrons from one body to another when they come in contact via rubbing or moving against each other. Shock is basically a mini feeling of current passing through your body. So now, let us look at these concepts in greater detail.

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What are Conductors?

Conductors are the materials or substances which allow electricity to flow through them. They are able to conduct electricity because they allow electrons to flow inside them very easily. Conductors have this property of allowing the transition of heat or light from one source to another.

Metals, humans, earth, and animal bodies are all conductors. This is the reason we get electric shocks! The main reason is that being a good conductor, our human body allows a resistance-free path for the current to flow from wire to our body.

Conductors have free electrons on its surface which allows current to pass through. This is the reason why conductors are able to conduct electricity.

Insulators

Examples of Conductors

  • Silver is the best conductor of electricity. However, it is costly and so, we don’t use silver in industries and transmission of electricity.
  • Copper, Brass, Steel, Gold, and Aluminium are good conductors of electricity. We use them mostly in electric circuits and systems in the form of wires.
  • Mercury is an excellent liquid conductor that finds use in many instruments.
  • Gases are not good conductors of electricity as the particles of matter are quite far away and thus, they are unable to conduct electrons.

Applications of Conductors

Conductors are quite useful in many ways. They find used in many real-life applications like:

  • Mercury is a common ingredient in thermometer to check the temperature of the body.
  • Aluminium finds use in making foils to store food and also in the production of fry pans to store heat quickly.
  • Iron is common in vehicle engine manufacturing to conduct heat.
  • The plate of an iron is made up of steel to absorb heat briskly.
  • Conductors find their use in car radiators to eradicate heat away from the engine.

Insulators

Insulators are the materials or substances which resist or don’t allow the current to flow through them. They are mostly solid in nature and are finding use in a variety of systems. They do not allow the flow of heat as well. The property which makes insulators different from conductors is its resistivity.

Wood, cloth, glass, mica, and quartz are some good examples of insulators. Insulators are also protectors as they give protection against heat, sound and of course passage of electricity. Insulators don’t have any free electrons and it is the main reason why they don’t conduct electricity.

Examples of Insulators

  • Glass is the best insulator as it has the highest resistivity.
  • Plastic is a good insulator and it finds its use in making a number of things.
  • Rubber is a common component in making tyres, fire-resistant clothes and slippers. This is because it is a very good insulator.

Applications of Insulators

Being resistive to flow of electron, insulators find application worldwide in a number of ways. Some of the common uses include:

  • Thermal Insulators, disallow heat to move from one place to another. We use them in making thermoplastic bottles, in fireproofing ceilings and walls.
  • Sound Insulators help in controlling noise level, as they are good in absorbance of sound. Therefore, we use them in buildings, conference halls, and buildings to make them noise-free
  • Electrical Insulators hinder the flow of electron or passage of current through them. We use them extensively in circuit boards, high-voltage systems and also in coating electric wire and cables.

Difference between Conductors and Insulators

Let us look at the basic difference between conductors and insulators in a nutshell.

Conductors

Insulators

A conductor allows current to flow through it. Insulators don’t allow current to flow through it.
Electric charge exists on the surface of conductors Electric charges are absent in insulator.
Conductor don’t store energy when kept in a  magnetic field Insulators store energy when kept in a magnetic field
Thermal conductivity ( heat allowance) of a conductor is very high Thermal conductivity of an insulator is very low
The resistance of a conductor is very low The resistance of insulator is very high
Copper, Aluminium, and Mercury are some conductors Wood, paper and ceramic are some insulators
Conductors are used in making electrical equipment. Insulators are used in insulating electrical equipment for safety purpose

Solved Example for You

Question: How can you increase the conductivity of water?

Solution: Water is a good conductor of electricity. However, if you want to increase its conductivity, you can add some salt to it.

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