Category Electricity

          You may have heard about conductors already. They are materials that allow electrons to flow freely from one particle to another. The capacity to transmit something such as heat or electricity is termed as conductivity. Depending on their conductivity, solids are classified as semiconductors, good conductors, and insulators.

           Objects that completely allow the passage of electricity are called good conductors. Pure silver is perhaps the best conductor we see around. Some liquids are good electric conductors too.

           Generally, gases are considered to be poor conductors. This is because their atoms are too far apart to allow free flow of electrons.

           Our body is said to be a good conductor of electricity. That is why we tend to receive electric shock from appliances or electric equipment.

           Insulators, on the other hand, do not permit the flow of electricity at all. Among the commonly seen insulators are glass, plastic, mica etc.

           Some materials like germanium and silicon belong to the category of semiconductors. This means they conduct electron flow under certain conditions. Otherwise, they act as poor conductors.

          The Ancient Greeks tried to study it some two thousand years ago. The man behind this attempt is known to be Thales of Miletus. He did research on the principle of static electricity.

          Around 585 BC, Thales conducted many experiments related to static electricity, a concept which was not conceived till then. He rubbed fur and clothes against amber to study more about the phenomenon.

          Amber is fossilized tree sap which is a plastic-like non-conducting material. Although he could not identify the secret force behind it, Thales was smart enough to see through attraction between unlikely objects. He could not have completed his study due to lack of resources and tools.

             The Greek contribution doesn’t end with this incomplete study. The very word ‘electricity’ has been derived from the Greek word ‘elektron’ meaning ‘amber’. 

       Static means steady, or unmoving. In physics, static electricity refers to that electricity which remains steady in a charged body. It is something that we come across in our daily life. An easy example could be the electricity produced when an object like a glass rod is rubbed against a piece of silk. Wonder how that happens? Let’s get to know.

       The fact that electric current is produced by the flow of electrons is something we already know by now. It is the friction between two objects that often result in this electron-transfer. This is how static charge is produced too.

         Take the example mentioned above. When a glass rod is rubbed against a piece of silk cloth, a few electrons from the rod moves to the cloth. As a result, the silk material turns negatively charged because of the excessive number of electrons. At the same time, having lost electrons, the rod becomes positively charged. As the process of rubbing continues, charge accumulated on the glass rod increases, and the pool of electrons that is formed on the other end creates what is known as ‘static electricity’. 

         Usually we talk about electricity as current. But are the two same? No!

         Let’s see why. As we have seen earlier, electricity is a form of energy. But electric current, on the other hand, is the movement of electric charge.

         Let’s put it better. It is the flow of charged particles through a medium such as a wire. Similar to water molecules moving down a river, charged particles move down a ‘conductor’ giving electric current. Conductor means anything that allows the movement of electric current for example, metals, and some liquids.

         Electric current is measured using a device called an ammeter. The conventional symbol for current is I.

        The intensity of electric current is measured in terms of ‘ampere’, named after the French scientist Andre-Marie Ampere, one of the founders of classical electromagnetism. 

          Electrons, as we know, are negatively charged subatomic particles. They are very important because of their role in various physical phenomena such as electricity, magnetism, etc.

           The history of electrons dates back to 1838, when Richard Laming put forth the concept of an indivisible quantity of electric charge to explain the chemical properties of atoms. Years later, in 1891, Irish physicist George Johnstone Stoney named this charge ‘electron’. Six years after that, British physicist J.J. Thomson identified the particle. The word ‘electron’ is thought to be a combination of the words ‘electric’ and ‘ion’.

           Inside the atom, electrons are in constant motion, revolving around the nucleus.

           They possess a certain amount of energy to maintain distance from the oppositely charged protons inside the nucleus.

         A proton is the positively charged subatomic particle located inside a nucleus.

         Protons are important because it is their number that determines the element (of which the atom is part) and its chemical properties.

         To put it simply, the number of protons in an atom, or the atomic number, defines the type of an atom. Thus an oxygen atom differs from a helium atom on the basis of its atomic number. That number is denoted by the letter ‘Z’.

         The word ‘proton’ was derived from a Greek word meaning ‘first’. It was named by Ernest Rutherford in 1920. One or more protons are present in every nucleus. Together, protons and neutrons form what is known as nucleons.

         Further, protons are made up of invisible particles called ‘quarks’. There is a strong nuclear force that binds these quarks with each other. It is also the same force that primarily contributes to the mass of the proton, rather than the quarks themselves.