Category Electricity

Electricity can make light and heat. It can also make a magnet. But this is a magnet you can turn on and off.

A magnet made with electricity is called an electromagnet. An electromagnet has two parts. The first part is a solid centre, or core, made of iron. The second part is an outer covering made of wire that is coiled many times around and around the solid iron core.

When an electric current runs through the wound wire, the iron becomes a magnet. The iron gets its pull, or magnetism, from the moving electrons in the wire. As soon as the electric current is turned off, an electromagnet loses its magnetism.

Electromagnets are used to make electric motors run. A motor has two sets of these magnets – an outer set that stays in place and an inner set that moves. The inner set of electromagnets is attached to an axle – a rod that can spin. When the motor is turned on, the two sets of electromagnets push and pull against each other. That push makes the inner magnets move and spin the axle. And the spinning axle gives a push that makes the motor run.

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A torch runs on electricity, but you don’t have to plug it in. It carries its own electric current in a “package” – a battery.

A battery is made of layers of chemicals inside a metal container. When the torch is turned on, some of the chemicals in the battery break apart and eat away at the metal container. As this happens, some of the metal atoms leave the container and combine with the chemicals inside the battery.

As the metal atoms move away from the container, they leave some of their electrons behind. So the container gains electrons. And as the chemicals inside the battery break apart, they lose electrons.

Soon, there are more electrons in the container than there are inside the battery. Then the extra electrons in the container begin to move out of the battery. They travel through the bulb and back into the middle of the battery, where electrons are scarce. The push of these electrons is the current that makes your torch shine.

It may sound as if everything happens very slowly, but, as you know, it all takes place in an instant.

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You want your electric clock to run day and night. But you wouldn’t want your doorbell ringing all the time. Things like doorbells, lamps, and radios work only when you turn them on.

Most things that run by electricity have a switch. A switch is used to turn the electric current on and off. The electric current moves along the wire and across the switch to another wire inside the bell, lamp, or radio. The switch is a “bridge” in the path the electricity follows.

A metal piece inside the switch moves when you turn the switch on and off. When you turn the switch on, the metal piece touches both wires. The “bridge” is down. The electricity coming into the switch can cross the “bridge” and keep travelling along the pathway.

When you turn the switch off, the metal piece moves away from the wire. The “bridge” is up. Without the “bridge,” the electric current can’t cross the switch and follow the path. So, the electric current stops moving, and things stop working until you lower the “bridge” in the pathway by turning the switch on again.

          Initially, direct current was used for power transmission. It was only in the 1950s that people realized the merits of alternating current over the other.

          Although the two are used today, alternating current is more accepted worldwide. It is used for bigger appliances as well as in houses. Let us see why.

          One of the main reasons for having AC for domestic purposes is that it causes very low wastage of power. It is seen that even at high voltages above 110 KV, less energy is lost in transmission. Yet another peculiarity of AC electricity is that voltage can easily be changed from high voltage to low and vice versa. This in turn makes it suitable for long distance transmission, unlike DC.

            Alternating current is also known to be capable of powering electric motors. Thus, it is useful for high-end appliances like refrigerators, televisions, computers etc.

            In terms of safety too, AC is preferred to DC power.

            It is for these reasons that most countries in the world favour AC than DC power. 

         Batteries can be broadly divided into two – primary and secondary.

         Primary batteries are single-use batteries – that are they can be used only once. After that, they should be discarded. They cannot be recharged. Quite a few non-rechargeable batteries are used in our daily life. This includes batteries used in toys, radios, remote controls, flashlights, clocks etc.

         Those batteries that can be recharged and reused are called secondary batteries. Through electric current, these batteries can be recharged.

         Secondary batteries can be seen in many devices including cell-phones, MP3 players etc.

         Yet another example can be seen in cars and trucks. Did you know that there is a lead-acid battery that works every time we start a car? This is how the car gets energy to run the lights and radio when the engine is not running. The battery in the car is recharged while we drive.

         Besides lead-acid, there are other batteries that can be recharged. This includes the nickel-cadmium battery, lithium-ion battery, nickel-metal hydride batteries etc.

          A battery is a device that stores electricity in chemical form inside a closed-energy system.

          Long before the invention of electrical generators and grids batteries proved to be the main source of electricity, and still continue to serve this purpose.

          There are batteries in different shapes. Some are very small, like the ones used in wristwatches, or smart phones, and some are as big as those used in cars and trucks. At the extreme, there are huge battery banks that are the size of rooms.

           All batteries have three parts- an anode (the negative side), a cathode (positive side) and an electrolyte, a liquid or gel that contains electrically charged particles called ions.

          When connected to an external circuit, the ions interact with the other two, and a chemical reaction takes place inside the battery.

          This reaction results in the generation of electric current. This is how batteries function and provide electric power to all appliances in our house including mobile, phones, laptops, flashlights etc.

           Batteries are devices that have been helping mankind for a long time. But nobody knows exactly when they were invented.

         An account of the earliest battery came in 1938 from Baghdad. The story goes that while constructing a railway line in the city, workers uncovered a pre-historic battery. Experts said that the battery belonged to the Parthian Empire, and was at least 2000 years old!

         Luigi Galvani, in 1786, was conducting an experiment when he accidentally touched a dead frog’s legs with two different metals. Suddenly the muscles of its legs contracted. He thought it was because of ‘animal electricity’. But his friend and fellow scientist Alessandro Volta didn’t agree. He guessed that the same effect would be produced if cardboard was soaked in salt water, instead of a frog’s leg. So, he stacked copper and zinc discs, separated by a cloth, and soaked them in salt water. He connected wires to either end of the stack.

                To his surprise, it produced stable current. Thus in 1800, Volta invented the ‘voltaic pile’, the first true battery that produced continuous and stable current. This is believed to have laid the foundation for the modern battery. 

           The Daniell cell is perhaps the first practical purpose battery ever. It was an electrochemical cell developed by the English chemist John Daniell in 1836. The cell offered a long-lasting source of power.

           Let’s see how the cell works. Daniell cell, consist of a copper pot filled with a copper sulfate solution, in which was immersed an unglazed earthenware container filled with sulfuric acid and a zinc electrode. The earthenware barrier which is porous, allows ions to pass through, but keeps the solutions from mixing.

           This cell produces current like a voltaic cell does, but with more efficiency. It soon became the industry standard for use. A voltage of over one volt is produced by a Daniell cell. To get a little more voltage, one has to increase the concentration of the solution in which the electrodes are dipped.

Electromagnetism is a basic force of nature. It is the creation of a magnetic field from the movement of electrical charges.

The basic characteristics of this force can be best defined through the example of a copper wire. When electric current is allowed to pass through the wire, it can attract, or magnetize pieces of iron or steel near it. That is, the electromagnetic force causes the attraction, as well as repulsion, of electrically charged particles.

There are two basic concepts behind electromagnetism. The first one is that, any moving charge produces a magnetic field because of its movement. The second one is that, a moving magnetic field can cause current to flow into a conducting loop. This means, if there is a moving bar magnet near a coil of wire that is connected to a meter, it can detect the current flow.

           The history of electromagnetism cannot be complete without a few names. Let’s take a look at a few of them.

           In 1820, Hans Christian Orsted, a professor at the University of Copenhagen, arranged an experiment for his students. He wanted to explain the heating of a wire by an electric current, and his experiment on magnetic property. For this, he used a compass needle mounted on a wooden stand. Suddenly, he noticed that every time the electric current was switched on, the compass needle moved. Orsted was surprised, and kept working on this for months to study how it happened. However, he was not successful. 

                                                                                                                                                                                                                                                                    But this experiment was taken further by another physicist in France named Andre-Marie Ampere. Through his study, he found out that wires with parallel currents attract each other, whereas those with anti-parallel current repel. He concluded that electricity can be governed by two sets of forces – electric and magnetic. 

Continue reading “Why is the history of the electromagnetic theory interesting?”

         Electromagnetism is a phenomenon that works behind almost all forces on Earth. Perhaps the only exception is gravity. Its influence is such that experts believe modern life is run through the electromagnetic phenomenon. Let’s try to understand what this means.

          Take the case of an electric fan. Its motor works on the principle of electromagnetic induction, which keeps it rotating on and on. This in turn, makes the blade hub of the fan to rotate, blowing air. Another example is that of a loud speaker. It is the electromagnetic force that is responsible for the movement of the coil inside. This in turn, results in the production of sound that can be heard over a long distance.

Continue reading “Why is it said that many of the phenomena that we witness in our daily life can explained by electro magnetic force?”

          An electromagnet is a device that can create a magnetic field if electricity is allowed to pass through it.

We can understand it better by comparing it with an ordinary magnet. In normal magnets, magnetic power is always present. But in electromagnets, the magnetic power or field depends on electricity. It can be turned on or off, using a switch. Likewise, the strength of these electromagnets can also be increased by increasing the amount of electric current.

                 There are different parts for an electromagnet. It consists of a coil of wire, made mainly of copper, and a piece of metal. The wire should be wrapped around the metal piece. When electric current is allowed to flow into the wire, a magnetic field is created around the coiled wire, and the metal gets magnetized. This is how an electromagnet is created.

                 Today, almost all equipment that we use, have electromagnets in them.

          The first recorded discovery about the relation between electricity and magnetism was made by Hans Christian Orsted in 1820.

           During an experiment, he noticed that the needle on his compass pointed to a different direction, when a battery near it was turned on. 

                                                                                                                                                                                                                                                                                                                      In 1824, William Sturgeon invented an electromagnet. It was made of a horseshoe-shaped piece of iron, wrapped with copper wire. He found out that when current was passed through the wire, it attracted the pieces of iron, and when the electric flow stopped, the magnetization ended too.

                By the 1830s, the US scientist Joseph Henry improved the design of the electromagnet. He used an insulated wire, and placed thousands of turns of wire on a single core. This made a big change! With this attempt, electromagnets gained more popularity. 

            There are different waves of light and energy that move around us.

            They come in the form of heat in the atmosphere, or radiation from space, or in any other form. These energy waves are commonly known as electromagnetic radiation. They have electric, as well as magnetic characteristics.

            The scientific definition given to this by experts goes as follows – the energy that is propagated through free space or a material medium in the form of electromagnetic radiation.

            Other than visible light, electromagnetic radiation includes radio waves, microwaves, infrared waves, ultraviolet rays X-rays, and gamma rays. They are classified on the basis of their frequencies or wave-lengths. The fact that the electromagnetic radiations are related to electromagnetism was put forward by a few scientists in the past. The existence of electromagnetic waves was first predicted by the Scottish physicist James Clerk Maxwell. In his electromagnetic theory that he put forth in 1864, he said that light is an electromagnetic disturbance in the form of waves.

           A few years later, German physicist Heinrich Hertz applied Maxwell’s theories to prove the existence of electromagnetic waves. 

 

          In its simplest terms, electromagnetic induction can be defined as the process where a conductor placed in a changing magnetic field causes the production of voltage across the conductor. This, in turn, causes or ‘induces’ an electric current.

         Many electrical devices that we see daily work on the principle of electromagnetic induction. A common use of this can be seen in electrical generators, transformers, induction cookers, musical instruments etc. The concept of electromagnetic induction was put forth in the early 1830s by the English physicist Michael Faraday.

           He conducted many experiments to study the idea. In one of it, he used a coil of wire, a permanent magnet and a device to detect voltage in the wire. When Faraday passed the magnet through the coil of wire, he saw there was a voltage induced and therefore current too. But it soon disappeared when the magnet stopped moving. From this, Faraday made a few observations. The most important one was that the induced voltage is the result of a changing magnetic field.

           In other words, Faraday discovered a way to produce electrical current by using the force of a magnetic field.

           The voltage induced is known as the electromotive force, or emf.

           Faraday’s findings led to a law linking electricity and magnetism known as the Faraday’s Law of Electromagnetic Induction. 

          Otto von Guericke was a German scientist, and inventor who lived between 1602 and 1686.

          He is credited to have made many inventions at a time when there were not many resources to refer to. One of it is the electrostatic generator, known to be the first one ever made.

          It was described as a huge sulphur ball, mounted on a pole inside a glass globe. With the help of a hand crank, the ball was rotated. As a result, the ball rubbed against a pad, generating sparks. This was static electricity, a phenomenon which they could not identify then. But the device became famous, and was used for later experiments with electricity.

            In 1672, Guericke found out that electricity produced through his earlier experiment could cause the surface of the sulphur ball to glow. The concept of electrostatic repulsion was demonstrated for the first time in history through Guericke’s book. 

          The simplest definition for the relay is that it is an electrically operated switch. The device is used where it is necessary to control a circuit by a low-power signal or where a number of circuits have to be controlled by one signal.

          Relays are controlled by electric current, magnetism or temperature. There are two types of relays – electromechanical and solid state. In the former, contacts are opened and closed using a magnetic force. With solid state relays, switching is done electronically.

          Electromechanical relays are general purpose relays. They are more common because they have lower cost, and can switch from AC or DC with equal ease.

Continue reading “Why did the relay make history?”

          A Leyden jar was the first device that could store electric charge. It was a glass jar with metal foil wrapped to its inside and outside surfaces. The jar would be partly filled with water, and had a wire running into it through the top part of the jar.

          There are two names involved with the invention of the jar. One is Ewald G. von Kleist, a German inventor who is said to have accidentally created it in 1745. The other is Pieter van Musschenbroek of Leyden, Holland, who ‘discovered’ the same thing in 1746. The latter invention spread through the world quickly, and thus Pieter gained more popularity for the invention.

          At first, it was thought that the electric charge was stored in the water inside the jar. In the 1700s, Benjamin Franklin studied much about this and proved that charge was stored in the glass. Hence, the later versions of Leyden jars had just metal foil wrapped inside and outside the glass.

          Technically, a Leyden jar is the prototype of the modern day capacitor which is used in almost all electronic equipment today.

                Benjamin Franklin invented the lightning rod in 1749. A lightning rod is a metal rod mounted on top of elevated structures like a building, tree, ship etc.

                It is electrically bonded with a wire with the ground or ‘earth’ through an electrode. Such an object protect a structure while lightning strikes. The idea behind it is that when lightning hits the building or tree, it will strike the rod.

              As a result, the electric power from lightning will be conducted to the ground through the wire, instead of passing through the building or tree. Thus, the structure can be saved from electrocution.

             Historians say that lightning rods were used in ancient times, and were particularly seen in the Sri Lankan kingdom of Anuradhapura, thousands of years ago. However, in the modern age, it was Benjamin Franklin who introduced the idea to the world. His aim was to create a tool that could save people from the dangers of the natural phenomenon. Through a series of experiments including the famous one using kite, he created the ‘Franklin rod’. 

            An electric motor is a device that converts electrical energy into mechanical energy. It works on the principle of electromagnetism.

            The first electrical motor is known to have been invented by a Scottish monk Andrew Gordon, in the 1740s. His motor was a simple electrostatic device.

            Almost a century later, British scientist Michael Faraday explained the conversion of electrical energy into mechanical energy by means of electromagnetism. The motor he created through the experiments was primitive, but it paved the way for later inventions. In 1822, British physicist Peter Barlow invented the first device to be powered by electromagnetism – known as Barlow’s Wheel.

            A decade later, British scientist William Sturgeon developed the first machine to be run on direct current. A few years after that, inventor Moritz Jacobi created the first real rotating electric motor that developed a remarkable mechanical output power. Frank Julian Sprague was the first to introduce a constant speed electric motor.

            All these have together contributed to the advancement of engineering technology in the world.

          An electronic amplifier is a tool that can amplify or increase the power, current, or voltage of a signal. It could be either a separate piece of equipment, or an electrical circuit within another device, but in general, amplifiers are used in almost all electronic equipment that we see around. They are particularly used in wireless communications and broadcasting.

          Before the amplifiers were introduced, mechanically coupled microphones were used to serve the purpose in telephone repeaters.

          In 1906, the triode was invented. It was the first electronic device that could amplify signals. It is a fundamental form of vacuum tube developed by the American inventor Lee De Forest. He had only a little understanding of how the tube worked.

          However, the discovery revolutionized electrical technology, and laid the foundation of electronics. It also made possible radio broadcasting, talking motion pictures, and countless other applications.

         An ammeter is an instrument used to measure the flow of electric current in a circuit. It measures current in terms of amperes, which is the unit of current. The speed and force of a current can be measured using this instrument.

         In the past, the instrument relied on the Earth’s magnetic field to take the readings of current. But as technology improved, better ammeters were designed and developed. Ammeters are mostly used in science laboratories. Other than scientists, electricians also use this instrument, to check the electric circuit.

        There are smaller units of reading to amperes, namely, milliamperes and microamperes. These are measured using milliammeters and microammeters respectively.

        There are two types of ammeters – analogue and digital. In analogue ammeters, there is a needle that points to the reading. In digital ammeters, they are displayed digitally.

        A voltmeter is an instrument that measures the voltage between two points in an electric circuit. It can be connected to a circuit by joining its positive and negative wires to where the voltage is. With such an arrangement, the instrument is said to be parallel to the electrical circuit.

       A voltmeter can be used for many purposes. For instance, to check whether there is any more electricity left in a battery.

       In an analogue voltmeter, the pointer indicates the number of volts. In a digital voltmeter, the reading will be displayed digitally. There are also voltmeters that can be mounted on a transformer, and other huge devices.

       Yet another variety is a voltmeter that uses amplifiers in them. Such meters can measure very small, or tiny voltages of microvolts, or even less.

         A galvanometer is a tool that measures the flow of electric charges through a wire. This basic device consists of a coil placed in a magnetic field. It can be used for detecting and comparing small electric currents.

        The ideas of galvanometers are known to have developed from an observation made by Hans Orsted in 1820. He had found out that the needle of a magnetic compass deflects near a wire that has electric current passing through it. But it was Johann Schweigger who built the first sensitive galvanometer in the same year. Galvanometers, since then, came to commercial use.

        A galvanometer can be used as an ammeter, as well as a voltmeter. By connecting a shunt in parallel to the coil, it acts an ammeter, and if the shunt is connected in series with the galvanometer coil, it becomes a voltmeter. 

          A multimeter is an instrument that measures the voltage, current, and resistance of an electrical device. Also known as a VOM (Volt-Ohm-Milliammeter), they are very useful in providing field measurements or detecting faults with accuracy.

          The first multimeter was invented by Donald Macadie, a British post office engineer who was unhappy with the need to carry separate instruments needed for the maintenance of telecommunication circuits. His invention was the instrument that could measure amperes, volts and ohms, and was named the avometer.

          The device is commonly used by electricians and other experts to troubleshoot problems on appliances, motors, circuits, power supplies and wiring systems. They could use the device on batteries, switches, power sources etc for measuring or diagnosing.

            Multimeters can be analogue or digital. Analogue multimeters are cheaper, but their readings are not as accurate as the digital meters. Recent digital multimeters are advanced enough to measure extremely tiny differences or fluctuations. 

          Direct current, as we know, is the flow of electric charge in just one direction. The history of electric power records that the first commercial transmission was made possible using direct current.

           This was perhaps because DC was the only option then. But as time passed, it proved to be insufficient. Because with direct current, voltage couldn’t be changed easily. What made it worse was that, different classes of loads, for instance, lighting, motors, and railway systems etc, required different voltages. So for this, there had to be different generators and circuits.

           However, in the course of time, alternating current took over and electric transmission became easier than before. We have seen that this type of current can reverse its direction, and serve better than DC. In 1884, the first long distance AC line was built in Italy, proving that AC was better for long distance transmission.

           As years passed, newer technologies were introduced. By the mid 1950s, an advanced type of direct current transmission was developed, and was named the high voltage direct current transmission. Today, it is the alternate and the most acceptable option for long distance, bulk transmission of electric power, especially between countries.

        Alternating current, as we saw, periodically reverses its direction, whereas direct current (DC) flows always in the same direction. The amount of current can change in a DC circuit, but their general direction remains the same.

         Perhaps the best and the simplest example of direct current is a battery. Take a look at one of them in your house. You can spot two terminals – +ve and -ve. If a wire is connected to these two terminals, it will cause a flow of electrons resulting in the production of electricity.

         Other than this, direct current is used as power supply for electronic systems and also for charging batteries. DC is thus used for many purposes, though for smaller and less complicated ones, unlike AC power. But direct current can be converted to alternating current through devices like an inverter or a motor-generator set.

         Direct current is produced by various sources such as solar cells, dynamos etc. It mainly flows in good conductors such as wire, but can also flow through semiconductors, insulators and even vacuum.

         Electric current in DC is measured in ampere and voltage in volts. 

        Electric current moves often like a water stream. The only difference here is that electric charges do not always move in the same direction. When they do, it is called Direct Current or DC.

        On the other hand, AC or Alternating Current, as the name suggests, occurs when charge carriers in a conductor, or semi conductor, reverse their direction of movement in a periodic manner.

        With AC, it is possible to run many types of electrical equipment like generators, motors, power distribution systems etc. and also kitchen appliances, TVs, electric lamps etc. Hence, for almost all high power applications, it is a global trend to use AC instead of DC because of its higher efficiency. Besides these advantages over DC, AC power is believed to be less expensive. One can also use high voltages with small currents to reduce losses, with AC power.

Continue reading “What is meant by AC?”

          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.

        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. 

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.

          Electric power transmission means the transfer of electric power from one place to another in large quantities.

           Typically, this happens between a power plant and a substation situated near a populated area. A substation is where voltage is transformed from high to low or vice versa using transformers. When power is transmitted from substations to consumers, the process is called power distribution. Normally, transmission takes place at very high voltage, like 110 kV or above. This is, because of the large amount of power involved in this.

            Over long distances, electricity is transmitted through overhead power transmission lines. But in places that are environmentally sensitive, or where there is very high population, transmission takes place underground. They have high installation cost and operational limitations, yet their maintenance cost is lower.

               The network of power stations, transmission lines, and substations is together known as a transmission grid. 

        From the moment power is generated in a plant, it goes through various stages before reaching our homes.

         Let’s see how power travels. From the electricity generating plants, current is sent through transformers to increase the voltage, so that it can be pushed longer distances.

         Electric power then reaches a substation. Here, the voltage gets lowered, so that it could be sent to smaller power lines.

         From there, it travels through various distribution lines, and reaches your neighbourhood where smaller transformers reduce the voltage, so that you can take safe power to your homes.

        From the transformer, power is carried through service drops, or smaller overhead electrical lines to your homes. It also passes through the ‘meter’ installed in the house that can measure how much power is used by the family.

        The current moves straight to the service panel, where fuses protect the wires inside the house from overloading. Keep in mind that children should never touch this panel!

         It is from here that power finally moves to the switches and outlets all over the house.

       Overhead power lines are structures for electric power transmission and distribution across large distances. They also make the cheapest method for transmitting power.

         In usual cases, overhead power lines have one or more conductors suspended by towers. One of the major duties of these power lines is to maintain enough space or clearance between these energized conductors and the ground, in order to avoid danger.

           These days, power lines can be operated at voltages of 765,000 volts or even more, between conductors. Depending on their range of voltages, overhead power lines can be classified as low voltage, medium voltage, high voltage, extra high voltage, and ultra high voltage.

              However, these power lines are extremely dangerous, and one has to keep a safe distance from them. Unlike household power cords, overhead power lines are not insulated. Even if it looks like insulation, it might be a weatherproofing material. 

       A transformer is an electrical device that transforms electricity from high to low voltage and vice versa. It is an important component for power transmission. Let’s get to know why.

       We saw the process through which electric power reaches our homes. When electricity travels from a power plant, it comes in a very high voltage. This is because the voltage from the plant is ‘stepped up’ by transformers before they are transmitted.

       The voltage has to be increased because electric power has to travel very long distances, and that too, with minimal loss of energy. We should know that energy is lost in the process of power transmission. But if the voltage is high, energy loss would be low.    

        But do our homes need this kind of voltage? Absolutely not! Before the power reaches houses, the voltage has to be lowered, or stepped down. This is where transformers again become important. They step down voltage from high to low. 

         Electric meters are devices that we commonly see in houses and offices. They are used to measure the total electrical energy consumed by the appliances in a house or office. The devices are installed by the electric power company that supplies electricity.

          If you take a close look at these meters, you can see a few digits. They denote the number of units of electricity that has been consumed so far. Our electricity bill depends totally on this reading.

          There are different types of electric meters available in the market. One is the electro-mechanical meter, which is most commonly used in our country. It has a magnetic metallic disc attached, which rotates, depending on the power passing through it. The rate of this rotation decides the reading on the meter.

          Then there are electronic meters that are popular in cities. In these, readings appear digitally on the display fixed on the meter.

          The newest in this league is the smart meter. They are electronic meters, but they have an added advantage. These smart meters are connected back to the utility (which provides us electricity) through the internet. Hence, no official will have to come in person and take the readings. The readings are sent through the internet, which makes the job easier. 

Electric power is always represented in terms of watts (W) or kilowatts (kW). A thousand watts together make a kilowatt.

Watts describe the rate at which electricity is consumed during a specific period. Take the case of a 15-watt LED bulb. It draws 15 watts of power at any moment when turned on.

Let’s look at other examples to understand the concept better. The power rating of a typical incandescent light bulb used in houses is between 25 to 100 watts. To produce a similar amount of light, fluorescent lamps consume 5 to 30 watts, and LED lamps use 0.5 to 6 watts.

Coming to power stations, a typical power station that uses coal to generate electricity produces around 600 to 700 megawatts. A megawatt is equivalent to one million watts! The term ‘watt’ was named after James Watt who developed the steam engine. Watt-hour is quite different from a watt. It is a measure of electrical energy equivalent to a power consumption of one watt for one hour.

      Short circuit is a term we hear often, and it is something that is dangerous, for sure. Let’s see what exactly a short circuit is.

       It is a problem that arises when two or more wires in an electrical circuit, that are not supposed to come in contact, touch each other. This action is immediately followed by a very high current flowing through the circuit. This can result in a lot of dangers, like sudden fire, destruction of the components in the circuit, or melting of insulation. Sometimes there can also be an electrical explosion, or what is known as an ‘arc flash’.

            Scary, isn’t it? However, there are fault protection devices like circuit-breakers and fuses that can detect a short circuit. 

          As we saw earlier, a fuse is a device that is provided in an electrical circuit to protect the appliances connected to it from damage. It is a safety tool that limits current in a circuit.

          Structurally, a fuse is a short piece of wire made up of elements like zinc, copper, silver, aluminium, which have high resistance, and a low melting point. In case of overheating due to excess current, the fuse tends to melt and separate. It thus prevents fire outbreaks and also protects humans from electric shock.

           Fuses, in general, are used in all types of electrical and electronic applications.

            Depending on their uses, there are different types of fuses available. One is the cartridge fuse, which is used to protect electrical appliances like motors, air-conditioners, refrigerators, pumps etc., where high voltage rating and currents are required.

           Then there are blade type fuses that come in a plastic body with two metal caps, to be fitted in a socket. These fuses are mostly used in automobiles for wiring and protection from short circuit.

           Another category is of reset-table fuses. They can be used multiple times without being replaced. Such fuses are seen in nuclear systems, or in aerospace systems.

       Telegraphy, a technology developed in the early 18th century, revolutionized long-distance communication. It was a simple electrical circuit that transmitted electric signals over a wire, between stations.

        Through the telegraph lines, messages could be sent back and forth as bursts of electricity. It was the connection between electricity and magnetism that led to this path-breaking invention.

           By the end of the 19th century, another invention surfaced – the telephone. It was a different and advanced device that improved communication between long distances. In a telephone, an electric current carries the sound. Here again, the invention followed the principle of electromagnetism.

          Another important device that works on the same principle is the loudspeaker. It converts an electrical signal from devices like a radio, or television into sound. For this purpose, the signals have to be connected to an electronic amplifier.

         Generally, a loudspeaker is built using a coil of thin copper wire, a still paper cone and a circular magnet. When electrical signals are passed through, the coil of copper wire moves back and forth. This, along with the magnet, causes the paper cone to vibrate and reproduce sounds.

          Taking into consideration the above mentioned devices, as well as other equipment, one can say that no invention in recent times has been complete without electricity. 

          The electrical sector of any country in the world depends mainly on its economic system, and policies adopted by its government.

          Hence, the whole process of power production and transmission in a country need not be the same as others. In some of them, generation, transmission and distribution of electricity are done by a government controlled organization. But in some others, privately owned companies will have shares too.

         Just like the operation, the voltage and frequencies for providing electrical power to appliances too, differ from country to country.

Continue reading “Why is it said that electricity distribution is different in every country?”

        The power sector of India is known to be one of the most diversified and powerful ones in the world. Sources of electricity generation here include conventional sources like coal, natural gas, oil, lignite, hydro and nuclear power, and also non-conventional sources like solar, wind, agricultural and domestic waste.

        The country has witnessed a very fast growth in electricity generation since 1990. In the year 2015, the country became a power surplus nation that possessed huge electric generation capacity. But many villages in India do not have power connection even now.

        By mid-2016, India’s power generation capacity crossed the 300,00 MW (megawatt) mark, including more than 42,848 MW renewable energy sources such as solar and wind power plants. This means, the country’s renewable energy sector is considered very important.

         About 65 per cent of the electricity produced in India is from thermal power plants. More than 20 per cent of the power comes from hydroelectric power plants and 3 per cent from nuclear plants. The rest is from alternate sources. 

          A power grid refers to an interconnected network for distributing electricity to consumers.

          It was in the 1960s that India began utilizing the grid management system on regional basis. The power grid system was then geographically divided into five regions for better management. These regions are – northern, eastern, western, north eastern and southern grids.

          They were established to enable the transmission of surplus electricity between states in each region.

          Towards the 1990s, the Indian government started planning for a national grid. As a result, the above mentioned regional grids were interconnected.

          In October 1991, the first interconnection was made, between the north eastern and the eastern grids. A few years later, in 2003, the western grid got connected with the above. This process followed in the later years as well. The northern grid was also interconnected in August 2006.

          In December 2013, the remaining grid- southern was connected to the central grid in a synchronous mode. Thus, the aim to build ‘One Nation – One Grid – One Frequency – was achieved.

           There are many reasons why renewable energy is important for the world and its future.

            The main advantage of these energies is that they are free of pollution. Renewable resources are way cleaner than fossil fuels because they don’t produce toxic wastes.

             Next, the reserves of these energies are never ending unlike coal, gas, oil or nuclear sources. Hence, they’re named renewables!

             Power production from fuels and other non-renewables demand a large-scale import of these resources at high prices. Also, their cost depends on the international market. In the case of renewable resources, it’s not needed as most of the energies depend on the Sun.

              There are many countries that depend largely on renewable resources. For instance, Denmark, UK, Scotland and Ireland make great use of wind energy.

              Denmark, which has been a pioneer in the field, gets around 42 per cent of its power from wind plants.

              And there are countries like China, and India that use of hydro power for electricity, which is equally safe.