Quarter 2 Week 1 - Introduction to Electromagnetic Radiation PDF

ELECTROMAGNETIC SPECTRUM Learning Competency: Compare the relative wavelengths of different forms of electromagnetic waves At the end of the lesson, you should be able to: Define electromagnetic wave. Explain the nature of EM wave. Describe how an electromagnetic (EM)...

ELECTROMAGNETIC SPECTRUM Learning Competency: Compare the relative wavelengths of different forms of electromagnetic waves At the end of the lesson, you should be able to: Define electromagnetic wave. Explain the nature of EM wave. Describe how an electromagnetic (EM) wave is produced and propagated Name significant proponents of formulation of electromagnetic wave theory PARTS OF THE WAVE CREST - The highest part of a wave. TROUGH - The lowest part of a wave. WAVELENGTH - distance covered by a full cycle of the wave, usually measured from crest to crest, or trough to trough. Wavelength is measured in m. AMPLITUDE - the maximum displacement of a point of a wave from its rest position. AMPLITUDE - the maximum displacement of a point of a wave from its rest position.  What is the difference between Transverse and longitudinal wave?  TRANSVERSE WAVE is a wave in which particles of the medium move in a direction perpendicular to the direction that the wave moves. LONGITUDINAL WAVE Is a wave in which particles of the medium move in a direction parallel to the direction that the wave moves.  ELECTROMAGNETIC WAVE Are waves that are created as a result of vibrations between an electric field and a magnetic field.  ELECTROMAGNETIC WAVE EM waves are produced by a charge that changes its direction or speed. Electrons are charged particles that can produce electric and magnetic fields. but in order to create the vibrating electric and magnetic fields that are the characteristics of an electromagnetic wave, electron must move. A changing magnetic field produces an electric field and in the same manner, a changing electric field produces magnetic field.  PROPERTIES OF ELECTROMAGNETIC WAVES EM waves are all transverse wave that propagates outward from a source perpendicular to the direction of the wave’s travel.  PROPERTIES OF ELECTROMAGNETIC WAVES The creation of EM waves begins with an oscillating charged particle, which creates an oscillating electric field and magnetic fields.  PROPERTIES OF ELECTROMAGNETIC WAVES EM waves travel in free space at the speed of 3x10^8 m/s or 300,000,00 m/s.  PROPERTIES OF ELECTROMAGNETIC WAVES EM waves possess different velocity of propagation in different medium. When travelling between media, the wavelength changes and therefore the speed of EM wave also changes. Also, this change is different for different frequencies.  DEVELOPMENT OF ELECTROMAGNETIC THEORY HANS CHRISTIAN OERSTED He is a Danish physicist and chemist who discovered that the electric current in a wire can deflect a magnetized compass needle, a phenomenon the importance of which was rapidly recognized and which inspired the development of electromagnetic theory. MICHAEL FARADAY He is probably best known for his discovery of electromagnetic induction. The changing magnetic and electric fields are perpendicular to each other their direction of propagation. Therefore, they are seen as transverse waves. JAMES CLERK MAXWELL He is an English scientist who developed a scientific theory to better explain electromagnetic waves. He described how electric charges and electric currents acts as sources of electric and magnetic fields that form the basis of the electric field of science and technology. HEINRICH HERTZ He IS A German physicist who applied Maxwell’s theories to the propagation and reception of radio waves. He was able to perform many experiments that helped explain, reflection, refraction, polarization, interference, and velocity of electric waves. The Hertz, SI unit of frequency is named after him. ANDRE-MARIE AMPERE He made the revolutionary discovery that a wire carrying electric current can attract or repel another wire next to it that’s also carrying electric current. WILHELM GILBERT He discovered that Earth was magnetic and theorized the electricity and magnetism are not the same. The gilbert, unit of magnetic potential, was named after him. WILHELM EDWARD WEBER He discovered that the ratio of electrostatic to electromagnetic units equals the value of the speed of light, leading to the conjecture that light is an electromagnetic wave. The weber, named after him, is the SI unit of magnetic flux. CHARLES AUGUSTIN DE COULOMB He developed Coulomb’s law, which defined the electrostatic force of attraction and repulsion. The coulomb, the SI unit of charge, was named after him. ALBERT EISTEIN He formulated the concept of the photoelectric effect. He was a German-born theoretical physicist who developed the theory of relativity, one of the two pillars of modern physics.  SEVEN TYPES OF ELECTROMAGNETIC WAVES IN AN ELECTROMAGNETIC SPECTRUM  RADIO WAVES They are produced by charges vibrating back and forth in radio and television transmitters. They are detected by radio and television receiving antennas. Radio waves are used in communication systems. Low frequency waves are used for AM radio and telegraphy; the high – frequency waves are utilized for FM radio and television communications. Their wavelengths range from 1mm to 100 km.  MICRO WAVES They are produced by vibrating charges in electrical circuits and transmitters. They are detected by radio and television receiving antennas. Microwaves are used for mobile communication, radar tracking, radio navigation, heating in microwave ovens, drying, and other industrial purposes. Their wavelengths ranging from 1x10^-3 to 3x10^-3 m.  INFRARED They are produced by molecular vibrations. Sources are warm objects. They are detected as heat or thermal radiation; strongly absorbed by objects and cause a rise in temperature. Using heat-seeking equipment, one can identify hot objects at night based on the infrared radiation they emit. Infrared sensitive cameras are used in medicine to detect some diseases. Their wavelengths ranging from 7x10^-7 to 1x10^-3 m.  VISIBLE LIGHT They are produced caused by the motion of electrons in an atom when they jumped between different orbits. Sources are hot objects such as fire and lamp. They are visible to the human eye and can be detected by photographic films. Lights enables us to see objects. It is used in optical fibers for medicine and communication. Plants need it for photosynthesis. The wavelengths of visible light are described as colors ranging from red (7x10^-7m) to violet (4x10-7m). The human eye’s sensitivity to the color of light is affected by the lights wavelength; It is greatest at yellow green, which has a wavelength of about 5.6x10-7m.  ULTRAVIOLET RAYS They are produced by motion of electrons in an atoms. Sources very hot objects such as the sun and mercury vapor lamps. They are detected by photographic films. Fluorescent materials absorb UV rays and radiate visible light called fluorescence. UV rays are used to sterilize medical equipment and kill unwanted bacteria. The wavelengths of UV rays ranges from approximately 10^-14 m to slightly less than 10^-10m.  X RAYS They are produced by motion of electrons in an atoms. Sources are x-ray tube. They are detected by special types of photographic films and fluorescent screens. X-rays are used for examining the interior of an opaque object, such that human body, and in analyzing crystal structures. The wavelengths of x-rays range from 0.1 x10^-9 m to 100x10^-9m.  GAMMA RAYS They are produced by motion of charged particles in the nuclei. They are detected by Geiger muller tubes and bubble/ cloud chambers. Gamma rays are used in medicine to eliminate cancerous growths and bacteria when sterilizing surgical instruments, and to study the functions of organs. The wavelengths of gamma rays range from 0.1 x10^-9 m to 100x10^-9m. TRANSMISSION AND PROPAGATION OF ELECTROMAGNETIC ENERGY GROUND WAVE PROPAGATION It is also known as Surface Wave propagation. It is a method of radiofrequency propagation that uses the area of the earth and the ionosphere for transmission that can propagate at frequencies below 3 MHz. SKY WAVE PROPAGATION It is also known as ionosphere Wave Propagation. It refers to the radio wave propagation via the ionosphere. This happens when electromagnetic waves travel towards the sky after propagation and reflect the earth from the ionosphere. SPACE WAVE PROPAGATION It is also known as Tropospheric Wave Propagation. It can travel directly or after reflecting from earth’s surface to the troposphere surface from the transmitter antenna to the receiver antenna. This is utilized in television and radar communications.