...Electromagnetic waves At this point in the course we'll move into optics. This might seem like a separate topic from electricity and magnetism, but optics is really a sub-topic of electricity and magnetism. This is because optics deals with the behavior of light, and light is one example of an electromagnetic wave. Light and other electromagnetic waves Light is not the only example of an electromagnetic wave. Other electromagnetic waves include the microwaves you use to heat up leftovers for dinner, and the radio waves that are broadcast from radio stations. An electromagnetic wave can be created by accelerating charges; moving charges back and forth will produce oscillating electric and magnetic fields, and these travel at the speed of light. It would really be more accurate to call the speed "the speed of an electromagnetic wave", because light is just one example of an electromagnetic wave. speed of light in vacuum: c = 3.00 x 108 m/s As we'll go into later in the course when we get to relativity, c is the ultimate speed limit in the universe. Nothing can travel faster than light in a vacuum. There is a wonderful connection between c, the speed of light in a vacuum, and the constants that appeared in the electricity and magnetism equations, the permittivity of free space and the permeability of free space. James Clerk Maxwell, who showed that all of electricity and magnetism could be boiled down to four basic equations, also worked out that: This clearly shows...
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...What exactly is the electromagnetic spectrum? Is a continuous range of wavelengths, which includes gamma rays, ultraviolet waves and other forms of electromagnetic radiation. How does the issue of scarcity and interference relate to the electromagnetic spectrum? The spectrum is considered scarce because of the limited number of frequencies for operation and two parties cannot broadcast on the same frequency in the spectrum. Interference not only can be caused by broadcasters but by natural phenomenons like thunderstorms. Another factor, which can attribute to interference is one known as Intermodulation. This happens when two or more frequencies affect each other’s transmission. What key decision did Congress make in 1927 in regards to the electromagnetic spectrum? In 1927 Congress declared that there could be no private ownership of the airwaves or spectrum; they were now considered public and could only be used with the approval and permission of the government. Who would own the electromagnetic spectrum? The airwaves were considered publicly owned. Who would be responsible for allocation of the spectrum and who would it be controlled by? Congress created a five member commission who now had the responsibility for allocation of the spectrum and controlling these allocations. What agency would be responsible for giving out licenses and was it free of charge or was it for a fee? What Congress considered a balanced five member commission which is today know as the...
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...Week 7 SPECTROSCOPY Learning outcomes • Describe what a photon is, and calculate the energy, frequency and wavelength of a given photon in relation to electromagnetic radiation. • Describe the process where a UV/visible photon is absorbed by an atom or molecule. • Interpret the data from UV/visible spectrum: – Complete dilution calculations in order to produce a standard curve. – Determine an equation for the line of best fit to a linear set of data. – Use the equation, y = mx + c in order to determine the concentration of an unknown solution. Electromagnetic Radiation • Electromagnetic radiation consists of an oscillating electric and magnetic field that carries energy through space at the speed of light, c, Amplitude c= × C = speed of light, 3.00 x108 m/s = wavelength, m = frequency, (number of waves per second) s-1 Maxwell ‘s description of behaviour of light Longer Lower Wavelength (SI unit : meter) Frequency (SI unit : second-1/ Hz) 1 MHz = 106 Hz 1 GHz = 109 Hz 1 THz = 1012 Hz 1 m = 10-6 m 1 nm = 10-9 m 1 pm = 10-12 m Example 7.1 The wavelength of the green light from a traffic signal is centered at 522 nm. What is the frequency of this radiation? Solution c= × ������ = Try this: 7.9 The average distance between Mars and Earth is about 1.3 x 108 miles. How long (in minutes) would it take TV pictures transmitted from the Viking space vehicle on Mars’ surface to reach earth? (1 mile = 1.61 km) ������������������������������������������������...
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...Sun and determine where the Sun is currently in its lifecycle.Light is a type of energy. Light behaves like a wave because it acts as a disturbance in the magnetic and electric field of space. Light can behave as a particle, because it sends all its energy to one place. A particle of light is called a photon. Photons can be absorbed into objects, bounce off objects, or fly through space. Scientists use the electromagnetic spectrum to organize and explain all types of electromagnetic energy that exist throughout the universe. Electromagnetic waves are organized in the electromagnetic spectrum according to their wavelength from the shortest, which are known as gamma rays to the longest which are known as radio waves. Electromagnetic energy is created by vibration. The vibration produces waves that carry energy. Each magnetic wave emits a different level of energy. These energies travel silently at the speed of light and produce a signature wave with a unique range of length, energy and frequency that scientists can identify and measure. One way that the energy of an electromagnetic wave is measured is by measuring its frequency. Frequency refers to the number of waves a vibration creates during a period of time. In general, the higher the frequency or number of waves, the greater the energy of the radiation and the lower the frequency or number of waves, the lower the energy of the radiation. Wavelength and frequency are inversely related meaning that the greater the length of...
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...Spectroscopy Nature of light The Electromagnetic Spectrum General Types of Spectra Continuous Spectra Emission spectra Absorption Spectra Types of Spectroscopy How Spectrometer work? Types of Spectroscopy Examples of Spectroscopy in Astronomy Probing the Formation of Stars in Colliding Galaxies in the universe. Uncovering the mystery of quasar Spectroscopy in Astronomy camp Stars like our own Sun Bibliography 1. Introduction Spectroscopy Spectroscopy is the study of matter and its properties by investigating light, sound, or particles that are emitted, absorbed or scattered by the matter under investigation. Spectroscopy may also be defined as the study of the interaction between light and matter. Historically, spectroscopy referred to a branch of science in which visible light was used for theoretical studies on the structure of matter and for qualitative and quantitative analyses. Recently, however, the definition has broadened as new techniques have been developed that utilize not only visible light, but many other forms of electromagnetic and non-electromagnetic radiation: microwaves, radiowaves, x-rays, electrons, phonons (sound waves) and others. Impedance spectroscopy is a study of frequency response in alternating current. Spectroscopy is often used in physical and analytical chemistry for the identification of substances through the spectrum emitted from them or absorbed in them. A device for recording a spectrum is a spectrometer. Spectroscopy can...
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...Conduction, Convection, and Radiation By: Spencer Smith Physics 2010 – Online Dr. Stone 30 April 2014 Physics is a controlling factor in our vast universe. It literally controls how our reality operates and how our existence came to be in this universe, it actually it what made our universe. When you think about physics you probably think about friction and forces but it is a much broader idea. Physics is what controls how the atoms that make up everything work with each other to form the things we see, the things we use, and even ourselves. Physics is a fundamental basis of our idea of the universe; yes there could be another parallel universe that has a different set of laws of physics but if it exists and we discover it physics will be there to help us understand the cause of this great phenomenon. Conduction, convection, and radiation are a processes of heat transfer and we experience these processes every day, some people might not realize it but these studies of physics are happening right now, all around us. Heat transfer is really just the transfer of energy and to understand how energy is transferred one must understand the physics of heat. “Conduction is the process of heat transfer in solids. If one end of a solid is heated, the particles of the solid gain kinetic energy thus moving faster. In a solid the particles are held together by strong forces of attraction. The only way in which the particles can move is to vibrate forwards and backwards. The...
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...This is how stars are formed and is a point in a star’s life. Astronomers determine composition, temperature, speed, and rotation rate of distant objects with a tool called a spectroscopy. When a star gives off light and the light splits by prism, the spectral pattern reflects a star’s composition. All stars are 95% hydrogen, so the variations in composition expose its age, luminosity, and origin. Composition of ages can be determined by observing the light of a star. The temperature of a star can be determined from its color and its spectrum. All stars have different colors because of its light radiation. Another way to determine the temperature of a star is to examine the spectral lines in the starlight. “Because we sometimes describe light as an electromagnetic wave, the complete spectrum of light is usually called the electromagnetic spectrum” (Bennett, Donahue, Schneider, and Voit, 2009). This is used to explain all types of electromagnetic energy that exist throughout the universe. Spectra consist of three different types: continuous, emission line, and absorption. Emission and absorption lines tells us that each type of atom, ion, or molecules obtain a rare set of energy levels. Every atom has its own rare spectral fingerprint because it has its own rare set of energy levels. If matter is made of hydrogen,...
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...October, 2014 Emission Spectrum & Absorption Spectrum In physics, when substances emit or absorb electromagnetic radiation, we use Spectrums to measure the emission or the absorption. Yet there’re two types of spectrum used to measure them— continuous spectrum and discrete spectrum. A continuous spectrum usually means a set of values for some physical quantity that is best described as an interval of real numbers. So what a continuous spectrum represents is a set of continuous data—there is no gaps of integer. As the diagram shows on the right, the relatively smooth parts are considered continuous spectrum. A discrete spectrum, however, contrary to the previous one, means a set of distinct values, which are discrete. So in the diagram above, the two tall sharp peaks are said to be discrete spectrum. As for lines spectrum, it is a spectrum with lines in it and those lines are products of a deficiency or an excess of photons compared with nearby frequencies. Finding the emission spectrum is relatively easy by using the flame test: The solution containing the relevant substance to be analysed is drawn into the burner and dispersed into the flame as a fine spray. The solvent evaporates first, leaving solid particles move to the hottest region of the flame where gaseous atoms and ions are produced. Here electrons are excited as described above. It is common for a monochromator to be used to allow for easy detection. 1.2 Spectrum "1 As for measuring the absorption spectrum: The most straightforward...
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...An X-ray is a form of high-energy electromagnetic radiation. (Basic Principle) Other types of electromagnetic radiation that make up the electromagnetic spectrum are microwaves, infrared light, visible light, ultraviolet light, and gamme rays. They all travel in waves, but possess different wavelengths. X-rays are shorter in wavelength compared to ultraviolet rays, but longer wavelengths when compared to gamma rays. (Comparison and Contrast) X rays are produced inside a vacuum tube called a Coolidge tube by the use of the principal cathode ray tube or an x-ray tube. (Location) In the case of the x-ray tube, the cathode and the anode have a voltage of 20-100 kV. The anode is typically made out of a substance called tungsten. Electrons emerging from the cathode hit the tungsten, loses energy from ionization and radiative collision, and results in x-rays and Brehmsstrahlung (white light photon). (Analysis) To be classified as x-rays, the frequency must range from 3x10^16 through 3x10^19 Hz. (Physical Description) The word X-ray, known as Roentgen rays in German-speaking countries, was named after its discoverer Wilhelm Conrad Rontgen. It was aptly named “X-rays,” with the “x” being a mathematical symbol for something unknown. He accidentally discovered it while experimenting with vacuum tubes in 1895. (Word Derivation) Strong, deeply penetrating, and highly destructive rays with short wavelengths are called hard X-rays. Those with longer wavelength and less penetrating...
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...sky blue? Many people ask this question and we think they come across as silly or young. But the ironic thing is, is that this question touches on some of the deepest aspects of astronomy and skygazing (Sky-Watch). The question is what causes us to see the sky as blue? There are a variety of answers and not necessarily all of them being true, like when you tell a child that it’s because God spilled his water. The sky is blue because of the wavelength of the colors in the electromagnetic spectrum, the atmosphere of Earth, and our eyes. Many people believe that the sky is light blue just because they have grown up to think only about the color blue when they are asked about the sky. But scientific studies show that the light from the Sun is all the colors of the rainbow. (Note card 3) The light travels in waves and consists of weightless particles that are moving around 200,000 kilometers per second (Sky-Watch). The range of light that our eyes can see is the electromagnetic spectrum. Each color in the spectrum has a different frequency-which is the number of cycles per second. The frequency of light is determined by color. For example, blue light has a shorter and highter frequency than the others. Furthermore, now you know that the light waves coming from the Sun contain all the colors with different frequencies and that the light with a lower frequency has a longer wavelength. For my second point, it is our atmosphere on Earth. In suppor of this we know that the light from...
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...lab http://phet.colorado.edu/sims/blackbody-spectrum/blackbody-spectrum_en.html t? How can you tell? 2. Does the light bulb produce X-rays? How can you tell? 3. In the spectrum made by the light bulb, which wavelength is most intense and what part of the electromagnetic spectrum is this? Wavelength _______________________ Type:_____________________ 4. Given your answer to #3 is an incandescent light bulb very good for its intended use? Explain. Click Save. (The curve will turn yellow) Part II Comparing spectra of different objects. Set the temperature to 615 K, this is comparable to the temperature in a very hot oven. Notice that the RED line is the radiation emitted by the oven. The line should appear flat, but it isn’t. Zoom the y axis in to read .001 and zoom the x-axis out to 12. 1. How is the curve produced by the oven similar to the line produced by the light bulb? 2. How is the curve produced by the oven different from the curve produced by the light bulb? 3. If the power goes out in your kitchen, could you see in the dark using light from the hot oven? Explain. Click Clear to clear the graphs. Set the temperature to 5800K. This is approximately the surface temperature of the sun. You’ll need to zoom in on the horizontal axis and zoom out on the vertical axis. 4. What is the most intense wavelength produced by the sun? What part of the electromagnetic spectrum is this? Wavelength _______________________...
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... USN: 1BY12EC014 Batch & Sem: V A Staff Incharge: Mrs Rashmi N, Asst.Professor Dept. of Electronics and Communication BMS Institute of Technology Signature of Student Signature of Faculty Signature of HOD TERAHERTZ TECHNOLOGY AND ITS APPLICATIONS Terahertz (THz) is Far-Infrared radiation located between microwaves and infrared in the electromagnetic spectrum. It is low-energy, non-ionizing radiation which can penetrate many non-polar, non-conducting materials such as clothing, paper, masonry or plastic. They can penetrate fog and clouds. Their wavelength corresponds revealingly with bio molecular vibrations. Terahertz radiation, also known as t-rays, has wavelength of 3-100 cm-1. Terahertz radiation was discovered in 1896. Unless they're at a temperature of absolute zero (−273.16°C), all objects, animate and inanimate, give off terahertz radiation (called T-rays), the heat from molecular vibrations. No one knew how to make T-rays bright enough to actually use in the everyday world. Attempts with semiconductors produced only wimpy T-rays, 1/2,000th of a watt at most. One way to make terahertz radiation is based on an ultra-fast laser. The THz band were initially being referred as “terahertz gap” due to two reasons. Firstly, there were not any proper and affordable signal sources, which are capable of transmitting signals in those frequencies, and secondly the neighbour frequencies...
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...field. Michael Faraday demonstrated the first electromagnetic induction and built the first direct current generator in 1831. In 1865 and again in 1873, famed Scottish physicist James Clerk Maxwell published multiple papers regarding electromagnetics. Alexander Graham Bell and Charles Sumner Tainter invented the photophone in 1880. The photophone was a telephone that conducted audio conversations wirelessly over modulated light beams, which required a direct line of sight. In 1885 Thomas Edison used a vibrator magnet for induction transmission. In 1891 he filed a wireless patent for the signal system and method using inductance he applied to the Lehigh Valley Railroad system he established in 1888. In the meantime, Henrich Hertz demonstrated the existence of electromagnetic waves with an oscillator. Then came what is perhaps the most debated topic in wireless history, the invention of the radio. WiFi has easily been one of the most useful technologies of the past decade so many of our daily tasks and the devices we use rely on it, and it’s on the verge of getting a whole lot better. First, it's not as new as it might sound. This is not a new idea or proposal it’s about the availability and use of white space for unlicensed devices in the TV bands as part of the FCC’s incentive auction process. The promise of the 600 MHz band, post incentive auction, is that the guard bands would mean that spectrum for unlicensed use would be available nationwide – in all markets...
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...Advanced Digital Signal Processing and Noise Reduction, Second Edition. Saeed V. Vaseghi Copyright © 2000 John Wiley & Sons Ltd ISBNs: 0-471-62692-9 (Hardback): 0-470-84162-1 (Electronic) 2 NOISE AND DISTORTION 2.1 Introduction 2.2 White Noise 2.3 Coloured Noise 2.4 Impulsive Noise 2.5 Transient Noise Pulses 2.6 2.7 2.8 2.9 2.10 Thermal Noise Shot Noise Electromagnetic Noise Channel Distortions Modelling Noise N oise can be defined as an unwanted signal that interferes with the communication or measurement of another signal. A noise itself is a signal that conveys information regarding the source of the noise. For example, the noise from a car engine conveys information regarding the state of the engine. The sources of noise are many, and vary from audio frequency acoustic noise emanating from moving, vibrating or colliding sources such as revolving machines, moving vehicles, computer fans, keyboard clicks, wind, rain, etc. to radio-frequency electromagnetic noise that can interfere with the transmission and reception of voice, image and data over the radio-frequency spectrum. Signal distortion is the term often used to describe a systematic undesirable change in a signal and refers to changes in a signal due to the non–ideal characteristics of the transmission channel, reverberations, echo and missing samples. Noise and distortion are the main limiting factors in communication and measurement systems. Therefore the modelling and removal of the effects of noise and...
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...SPECTRUM ALLOCATION PROCESS IN INDIA What is Spectrum The word spectrum refers to a collection of various types of electromagnetic radiations of different wavelengths. Spectrum or airwaves are the radio frequencies on which all communication singnals travel. In India the radio frequencies are being used for different types of services like space communication, mobile communication, broadcasting, radio navigation, mobile satellite service, aeronautical satellite services, defence communication etc. Radio frequency is a natural resource but unlike other resources it will deplete when used. But it will be wasted if not used efficiently. The spectrum allocated to Indian telecom operator is most crowded and inadequate to accommodate the usage by 650 million mobile subscribers as on date. This has affected the quality of customer service and resulted in poor voice quality, call drop and undelivered messages of mobile services in India. ++++++++++++++++++++++++++++++++++++++++++++++++++++++===== ------------------------------------------------- Spectrum Management at International Level ------------------------------------------------- Agencies allocating spectrum : ------------------------------------------------- ------------------------------------------------- Spectrum allocation is important and necessary to ensure interference free operation for each radio service. All nations share the electromagnetic spectrum and reserve their right to its ------------------------------------------------- ...
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