The UPSC mains GS-3 paper syllabus has various subjects like Economics, Science and Technology. Science and technology in UPSC is mostly concerned with current Affairs. but it is necessary to understand the basics of science.
TOPICS
- What is Electricity and magnetism ?
- What is electricity?
- What is magnetism?
WHAT IS ELECTRICITY AND MAGNETISM?
- Electricity and magnetism are one of the most interesting topics in physics. In this article, we will learn about the concepts of magnetism and electricity and the relationship between them. We shall also learn the magnetism and electricity definition, interesting concepts like electron movement, conductors, semiconductor and insulators, and magnetic field
What is Electricity?
Electricity is the presence and motion of charged particles. How does energy travel through copper wire and through space? What is electric current, electromotive force, and what makes a landing light turn on or a hydraulic pump motor run? Each of these questions requires an understanding of many basic principles. By adding one basic idea on top of other basic ideas, it becomes possible to answer most of the interesting and practical questions about electricity or electronics. Our understanding of electric current must begin with the nature of matter. All matter is composed of molecules. All molecules are made up of atoms, which are themselves made up of electrons, protons, and neutrons.
Electricity is often described as being either static or dynamic. The difference between the two is based simply on whether the electrons are at rest (static) or in motion (dynamic). Static electricity is a build up of an electrical charge on the surface of an object. It is considered “static” due to the fact that there is no current flowing as in AC or DC electricity. Static electricity is usually caused when non-conductive materials such as rubber, plastic or glass are rubbed together, causing a transfer of electrons, which then results in an imbalance of charges between the two materials. The fact that there is an imbalance of charges between the two materials means that the objects will exhibit an attractive or repulsive force.
Electron Movement
The valence of an atom determines its ability to gain or lose an electron, which ultimately determines the chemical and electrical properties of the atom. These properties can be categorized as being a conductor, semiconductor or insulator, depending on the ability of the material to produce free electrons. When a material has a large number of free electrons available, a greater current can be conducted in the material.
Conductors
Elements such as gold, copper, and silver possess many free electrons and make good conductors. The atoms in these materials have a few loosely bound electrons in their outer orbits. Energy in the form of heat can cause these electrons in the outer orbit to break loose and drift throughout the material. Copper and silver have one electron in their outer orbits. At room temperature, a piece of silver wire will have billions of free electrons.
Insulators
These are materials that do not conduct electrical current very well or not at all. Good examples of these are glass, ceramic, and plastic. Under normal conditions, atoms in these materials do not produce free electrons. The absence of the free electrons means that electrical current cannot be conducted through the material. Only when the material is in an extremely strong electrical field will the outer electrons be dislodged. This action is called breakdown and usually causes physical damage to the insulator.
Semiconductors
This material falls in between the characteristics of conductors and insulators, in that they are not good at conducting or insulating. Silicon and germanium are the most widely used semiconductor materials. For a more detailed explanation on this topic refer to Page 10-101 in this chapter.
What is Magnetism?
Magnetism is a concept introduced in physics to help you understand one of the fundamental interactions in nature, the interaction between moving charges. Like the gravitational force and the electrostatic force, the magnetic force is an interaction at a distance.
What is a Magnetic Field?
Magnetic fields, like gravitational fields, cannot be seen or touched. We can feel the pull of the Earth’s gravitational field on ourselves and the objects around us, but we do not experience magnetic fields in such a direct way. We know of the existence of magnetic fields by their effect on objects such as magnetized pieces of metal, naturally magnetic rocks such as lodestone, or temporary magnets such as copper coils that carry an electrical current. If we place a magnetized needle on a cork in a bucket of water, it will slowly align itself with the local magnetic field. Turning on the current in a copper wire can make a nearby compass needle jump. Observations like these led to the development of the concept of magnetic fields.
Difference Between Electricity and Magnetism
- There are numerous ways by which we can differentiate between magnetism and electricity. Some main electricity and magnetism differences are given in the points mentioned below.
- The major difference between electricity and magnetism is the presence of magnetism.
- Electricity can be present in a static charge, while magnetism’s presence is only felt when there are moving charges as a result of electricity.
- In simple words, electricity can exist without magnetism, but magnetism cannot exist without electricity.
What is Electromagnetic Radiation?
Sun is the ultimate source of energy. It is an eternal source of natural energy and has a great potential for a wide variety of applications because it is abundant and accessible. The emitted light of the sun is in the form of electromagnetic energy, but visible light is only a small portion of the electromagnetic spectrum. In this article, we are giving the concept of Electromagnetic Radiation, its characteristics and theory which is very useful for the competitive examinations like UPSC-prelims, SSC, State Services, NDA, CDS, and Railways etc.
Sun is the ultimate source of energy. It is an eternal source of natural energy and has a great potential for a wide variety of applications because it is abundant and accessible. The emitted light of the sun is in the form of electromagnetic energy, but visible light is only a small portion of the electromagnetic spectrum, which contains a broad range of electromagnetic wavelengths. The electromagnetic waves in sunlight ranging from infrared (IR) to ultraviolet rays (UV). The visible light from the sun is in between IR and UV in the electromagnetic spectrum. The emission or transmission of energy in the form of waves or particles through space or through a material medium is called radiation.
What is Electromagnetic Radiation?
Electromagnetic radiation is a form of energy that is produced by oscillating electric and magnetic disturbance, or by the movement of electrically charged particles traveling through a vacuum or matter.
The electromagnetic radiation emitted from the outer surface of the sun consists of four spectra of radiation waves are given below:
- The first spectrum of the electromagnetic waves includes gamma rays, hard x-rays, soft x-rays and ultra violet rays.
- The second spectrum of the electromagnetic radiation waves also called the spectrum of visible light includes violet, blue, green, yellow, orange and red rays.
- Third spectrum of the electromagnetic radiation waves is called as infrared spectrum.
- Fourth spectrum of the electromagnetic radiation waves consists of long waves including microwaves, radar waves and radio waves.
Characteristics of Electromagnetic Radiation
- The range of electromagnetic waves is called electromagnetic spectrum.
- Electromagnetic spectrum is divided into seven regions, i.e. Radio waves; Microwaves; Infrared (IR) waves; visible light; Ultraviolet (UV) rays; X rays; and Gamma rays.
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