Category Physics

What is meant by electric current?

         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. 

Who identified the electron?

          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.

 

Why was the discovery of protons important?

         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.

 

Why is electric charge important?

        Electric charge is the physical property of matter.

        There are two types of electric charges: positive and negative. Like charges (positive and positive, for example) repel, and unlike charges (positive and negative) attract. The most common charge carriers are the positively charged proton and the negatively charged electron. An object is negatively charged if it has an excess of electrons.

        As per the International System of Units (SI), the unit of electric charge is coulomb, which is equivalent to about 6.242×1018 e. In electrical engineering, the unit is seen as ampere-hour (Ah), and, in chemistry, it is common to use the elementary charge (e) as a unit.

        By convention, the charge of an electron is -1, while that of a proton is +1. The quantity of electric charge can be measured with an electrometer.

        The study of charged particles, and how their interactions are mediated by photons, is called quantum electrodynamics. 

Why is it said that the wind and tides are the best way to produce electric power?

        The wind is a major source of renewable energy that is also useful to generate power. You must have seen windmills in real life, or on television. They are set up on farms for power generation.

        Although they look like fans, windmills work in just the opposite way. In fans, electricity is used to make wind, but in windmills, wind is used to make electricity.

        Let’s see how they work. When the wind blows, it turns the blades of the windmill. This in turn, spins a generator inside, and produces electricity.

         A single windmill can generate only a small amount of electricity. Hence, power companies build wind farms with a large number of wind turbines.

        In many countries including Denmark and Portugal, wind power contributes largely to power production.

        Yet another form of energy comes from ocean tides, which again, can be used to produce electricity. Just like wind turbines, there are tidal turbines too. They are turned by ocean currents. The spinning turbines are connected to devices that generate electricity.

         Here again, the process and products are safe, as there are no harmful emissions made.

 

How do solar power plants work?

As the name suggests, solar power plants use sunlight for power production. There are two different technologies used for solar power production these days- using photovoltaic plants and solar thermal systems.

Photovoltaic cells, or PV cells, produce electric current when exposed to light. They are also called solar cells. They contain silicon, a naturally occurring element found in sand. When sunlight hit silicon, there happens a chemical reaction. As a result, electrons move, and electric current is produced. A group of PV or solar cells create a solar panel. A number of solar panels form a solar array, and they generate solar energy.

In solar thermal systems, sunlight is collected and concentrated to produce high temperature heat that is needed to generate electricity. All the systems have solar energy collectors with two components – a ‘reflector’ that captures and focus sunlight onto the ‘receiver’. In the system here, a heat transfer liquid is heated and circulated in the receiver. It is used to produce steam. The steam is then converted to mechanical energy in a turbine, which powers a generator to produce electricity.