Category Electricity

       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.