Does Glass Conduct Electricity?

Does glass conduct electricity

Glass is a non-crystalline and amorphous solid with transparent luster. It is made up of silicon and oxygen atoms connected in a chain-like structure forming a lattice crystal. It is prepared by quenching (rapid cooling) process. Some glasses like volcanic glasses are naturally occurring. Many of you have a doubt regarding whether glass conducts electricity or not. In this article, we will study whether glass conducts electricity or not.

So, Does glass conduct electricity? Glass is an insulator at room temperature due to the large bandgap and has no free electrons. Glass consists of Oxygen atoms that have high electronegativity and bound the electrons strongly. This is because a high amount of energy is required to free the electrons from Oxygen atom so that glass can conduct electricity. Therefore, at room temperature, the glass acts as an insulator.

Glass is a transparent amorphous substance with a wide range of applications across the globe. It is majorly produced by the rapid cooling of the molten solution.

Sand is the primary constituent of the silicate glass ie; one of the oldest forms of glass. It consists of silicon dioxide (SiO2) molecules also known as quartz.

It is an inorganic non-metallic material and can be considered as virtually solid liquids that are cooled rapidly.

Glass has wide applications like drinking bottles, windows, optical glass, etc. Sand being a primary constituent can itself be converted into a glass by heating it on a temperature of 1700 degrees Celcius.

1 silicon and 2 oxygen atoms covalently bond to form Silicon dioxide molecules arranged in the structure.

silicon oxygen glass

Keeping in mind that oxygen has high electronegativity and bounds its valence electrons strongly. This means a high amount of energy is required to free the electron from the oxygen atom.

glass molecules


Why glass is an insulator?

For any compound to conduct electricity, it is necessary to have free electrons. As free electrons are the carriers that flow the electric current throughout the material.

The more the free mobile electrons present in a substance more is its conductivity. Therefore, metals are good conductors fo electricity as the have cloud of free mobile electrons to flow the electric current on applying a voltage.

If we talk about the glass, there are no free electrons present inside the material. As it contains silicon and oxygen forming SiO2 molecules that are stable at room temperature.

Apart from free electrons, it has a large bandgap.

Band Gap: it is the minimum difference between the energy of the electronic shell in which an electron is bound to its atom and the electronic shell in which an electron is free to move across the lattice.

Silicon and oxygen form a stable molecule left with no free electron and oxygen being a high electronegative atom bounds its electron strongly.

As a result, a high amount of energy is required to free the electron from the glass material. it is not possible for glass to have free mobile electrons at room temperature.

Therefore, the glass acts as an insulator.


Effect of temperature on the electrical conductivity of Glass

At room temperature, the glass is a good insulator as there exist no delocalized ions to move freely and conduct electricity.

Therefore, it requires a strong electric field to break down the electrons out of lattice to move freely as a carrier to flow current.

Glass is an amorphous solid due to which it gets soften slowly on heating it. As we increase temperature, few electrons become able to move freely.

On further raising the temperature, the viscosity of glass decreases, and the number of free electrons in the glass increases, and more electrons get free to conduct electricity.

Once the glass gets soften, on increasing the temperature, the electrical conductivity of glass also increases.

Types of Glass

There are different types of glass having different types of chemical composition. The composition varies as per its uses.

Silicate glass

  • This type of glass has mainly SiO2 as its constituent.
  • low thermal expansion
  • Thermal shock resistant
  • It can resist high-temperature conditions.
  • It has a high melting point ranging 1700 degrees celsius.

silicate glass

Soda-lime glass

  • The main constituent is Sodium Carbonate (Na2CO3)
  • High thermal expansion.
  • Poor heat resistance.
  • Lime, Magnesia, and alumina are added to improve chemical durability.
  • Mostly used as windows and tables and jars.

soda lime glass

Borosilicate glass

  • It mainly contains Boron trioxide
  • Low thermal expansion
  • Mainly used for labs and household appliances.

borosilicate glass

Lead glass

  • It is formed by the addition of lead oxide in silicate glass.
  • PbO2 is added in silicate glass to lower down the temperature.
  • It has high elasticity
  • Cannot bear high temperature

lead glass

Aluminosilicate glass

  • It contains 5 to 10% of alumina (Al2O3)
  • High thermal resistance and durability
  • Used for cookware and fiberglass.

How glass is prepared from sand?

  • Sand is heated up to high temperature so that it melts completely.
  • Apart from sand, other chemical like calcium carbonate, sodium carbonate is also added and heated in the furnace at high temperatures.
  • Sodium carbonate and calcium carbonate reduces the melting point of sand to reduce energy consumption in the overall process.
  • Once the mixture with sand melts, it is poured into the dyes of the desired shape like oval, flat glass, etc.
  • And, the air is blown at ends of the pipe for cooling.

Properties of Glass

  • Viscosity: In a molten state, glass is a highly viscous fluid that manufacturers maintain at a specific range of temperatures to work on it to mold it in the desired shape.
  • Strength: The glass surface is added with crystals and flaws to enhance its strength. Different glasses have different kinds of strength like compressive, tensile, etc.
  • Thermal Expansion: glass has a tendency to expand on higher temperatures. Different types of glasses have different coefficients of thermal expansion.
  • Electrical conductance: As explained above, the glass has high bandgap among its molecules. As a result, at room temperature, it acts as an insulator.
  • Thermal conductivity: Glass is a non-crystalline material. It has a low thermal conductivity of around 0.8 W/m K.


Uses of Glass

  • Glass has an unlimited number of uses.
  • It is used as windows and doors in the home and offices.
  • It is used for making tableware like cups, jars, bowls, etc.
  • Beverage bottles are mostly made up of glass.
  • It is used for the interior design of houses due to its transparent and shiny texture.
  • It has its great use in medical fields like optical glasses and medical appliances, etc.


Being an amorphous substance and having no free mobile ions, glass do not conduct electricity and considered a good insulator. It mainly consists of SiO2 molecules with covalently bonded atoms and it requires a strong electric field to break down the electrons to conduct electricity. Therefore, at room temperature, it acts as a good insulator.

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