Category Physics

           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.