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Conductors and Insulators

Last Updated : 21 Jul, 2021
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When humans remove synthetic clothing or sweater, especially in dry weather, he or she often sees a spark or hear a crackling sound. With females’ clothing like a polyester saree, this is essentially observed. Another example is Lightning a common form of electric discharge that seen in the sky during thunderstorms, the sensation of being electric shock while opening a car door or while grabbing a bus’s iron bar after sliding off our seats.  

The cause of these sensations is the discharge of electric charges that have collected as a result of rubbing insulating surfaces. This is related to static electricity generation.  Anything that does not move or change through time is referred to as static. The study of forces, fields, and potentials coming from static charges is known as electrostatics.


A metal rod brushed with wool in the hand will not exhibit any signs of being charged. A metal rod with a wooden or plastic handle, on the other hand, exhibits symptoms of charging when rubbed with wool without touching its metal section. Assume one end of a copper wire is connected to a neutral pith ball and the other end is connected to a negatively charged plastic rod. It is observed that the pith ball will acquire a negative charge. When a comparable experiment is carried out with a nylon thread or a rubber band, no charge is transferred from the plastic rod to the pith ball. 

Some materials readily enable electricity to pass through them, whereas others do not. Conductors are materials that allow electricity to flow freely through them. They have comparatively free-moving electric charges (electrons) inside the material. Conductors include metals, human and animal bodies, and the ground itself. 

Electrical circuits and equipment benefit from earthing as a safety measure. A big metal plate is placed deep in the soil, and thick wires are dragged from it; these cables are utilized in buildings to earth near the mains supply. Our homes’ electrical wiring consists of three wires: live, neutral, and earth. The first two carry electric current from the power plant, while the third is earthed by being connected to the buried metal plate. The earth wire is connected to the metallic body of electric equipment such as electric irons, refrigerators, and televisions. When a malfunction occurs or a live wire comes into contact with the metallic body, the charge flows to the earth without destroying the appliance or injuring humans; this would have been unavoidable otherwise because the human body is a conductor of electricity.

Applications of Conductor

Conductors are quite handy in a variety of situations. They’re useful in a variety of situations. As an example,

  • Mercury is a frequent component of thermometers used to measure body temperature.
  • Aluminum is used in the manufacture of food-storage foils. It’s also used to make fry pans that can hold heat for a long time.
  • Iron is a typical heat-conducting material used in car engine production.
  • The iron plate is made of steel to quickly absorb heat.
  • Conductors are used in automobile radiators to transfer heat away from the engine.

Examples of Conductors

  • Silver is the most effective conductor of electricity. However, because silver is expensive, it is not used in industry or for energy transmission.
  • Copper, brass, steel, gold, and aluminum are excellent electrical conductors. In the shape of wires, we use them in electric circuits and systems.
  • Mercury is a great conductor of liquids. As a result, this material is used in a variety of instruments.
  • Because the atoms are so far apart, gases are poor conductors of electricity. As a result, they can’t conduct electrons.


Most non-metals, such as glass, porcelain, plastic, nylon, and wood, have a high resistance to the transmission of electricity. They are called insulators. Insulators are materials that prevent electrons from freely flowing from one element’s particle to another. If a charge is applied to such an element at any point on the surface, the charge remains in the same place and does not spread throughout the surface. Charging by rubbing (for some elements, with the help of suitable materials) and charging by induction are two typical methods for charging such components.

When a charge is transmitted to a conductor, it quickly becomes charged. Dispersed across the conductor’s whole surface If, on the other hand, some When a charge is applied to an insulator, it remains stationary. This material property explains why a nylon or plastic comb is preferred. When combing dry hair or stroking it, it becomes electrified, while a metal piece does not. The charges on metal pass through our bodies to the ground. Both the ground and the body are electrical conductors. 

Applications of Insulators

  • Insulators are used all around the world because they prevent electron flow. Among the most common applications are:
  • Thermal insulators prevent heat from moving from one location to another. As a result, they’re used to making thermoplastic bottles. They’re also utilized to fireproof walls and ceilings.
  • Sound insulators are useful for controlling noise levels since they absorb sound well. As a result, we employ them to make buildings and conference spaces noise-free.
  • Electrical insulators obstruct electron flow and current flow via them. As a result, we frequently utilize them in circuit boards and high-voltage systems. Electric wire and cables are also coated with them.

Examples of Insulators

  • Because of its high resistivity, glass is the best insulator.
  • Plastic is a good insulator and is used to make a variety of items.
  • Rubber is commonly utilized in the manufacture of tyres, fire-resistant clothing, and shoes. This is due to the fact that it is an excellent insulator.

Difference between Conductors and Insulators.



A conductor is a material that permits current to flow freely through it.

Insulators prevent current from flowing through them.

Electric charge exists on the surface of conductors.

Electric charges are absent in the insulator.

Conductors don’t store energy when kept in a magnetic field.

Insulators store energy when kept in a magnetic field.

The thermal conductivity ( heat allowance) of a conductor is very high.

Insulators store energy when kept in a magnetic field.

Conductors don’t store energy when kept in a magnetic field.

Insulators store energy when kept in a magnetic field.

The thermal conductivity ( heat allowance) of a conductor is very high.

The thermal conductivity of an insulator is very low.

The resistance of a conductor is very low.

The resistance of the insulator is very high.

Sample Questions

Problem 1: What do you mean by Charging by Friction?


The charging by friction method includes rubbing one particle against another, causing electrons to move from one surface to the next. This procedure can be used to charge insulators. 

Different types of atoms and atom combinations make up material objects. Various items have different electrical characteristics due to the existence of different atoms in them. Electron affinity is one of these properties. Simply described, electron affinity is a feature that describes how much a substance cares about electrons. If a substance’s atoms have a high electron affinity, the material will have a strong affection for electrons as well. As one of the most prevalent types of charging, turboelectric charging, commonly known as charging by friction or rubbing, this property of electron affinity will be crucial. 

Problem 2: If 109 electrons move out of a body to another body every second, how much time is required to get a total charge of 1 C on the other body?


In one second 109 electrons move out of the body. Therefore, the charge given out in one second is

1.6 × 10–19 × 109 C = 1.6 × 10–10 C.

The time required to accumulate a charge of 1 C can then be estimated to be

1 C / (1.6 × 10–10 C/s)

= 6.25 × 109 s = 6.25 × 109 / (365 × 24 × 3600) years

= 198 years.

Thus, to collect a charge of one coulomb, from a body from which 109 electrons move out every second, we will need approximately 200 years. One coulomb is, therefore, a very large unit for many practical purposes. It is, however, also important to know what is roughly the number of electrons contained in a piece of one cubic centimeter of material. A cubic piece of copper of side 1 cm contains about 2.5 × 1024 electrons. 

Problem 3: Does pure water conduct electricity? If not, what can we do to make it conducting?


No, pure water doesn’t conduct electricity. When salt is dissolved in pure water, it conducts electricity as it provide it with ions needed to conduct electricity.

Problem 4: How much positive and negative charge is there in a cup of water?


Let us assume that the mass of one cup of water is 250 g. The molecular mass of water is 18 g. Thus, one mole (= 6.02 × 1023 molecules) of water is 18 g. Therefore, the number of molecules in one cup of water is (250/18) × 6.02 × 1023. Each molecule of water contains two hydrogen atoms and one oxygen atom, i.e., 10 electrons and 10 protons. Hence, the total positive and total negative charge has the same magnitude. It is equal to

(250/18) × 6.02 × 1023 × 10 × 1.6 × 10–19 C

= 1.34 × 107 C.

Problem 5: What is Coulomb’s Law?


According to Coulomb’s law, the force of attraction or repulsion between two charged things is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. It acts along the line that connects the two charges that are regarded to be point charges.

Coulomb studied the force between two point charges and found that it is inversely proportional to the square of the distance between them, directly proportional to the product of their magnitudes, and acting in a line that connects them.

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