The Electromagnetic Spectrum - Report Example

s the assignment was due Visible Light, IR, X-rays and UV The magnetic and electric components of a vibrating electric charge produce the electromagnetic ways. The electric field and magnetic field of the electromagnetic waves are at right angles to each other and these ways occur in a huge range of frequencies. This enormous range of frequencies is termed as the electromagnetic spectrum. Based on the wavelength and frequency, the huge spectrum can be subdivided into smaller regions such that, the low frequency long wavelength regions are located at one end of the spectrum while the high frequency low wavelength regions occupy the other end of the spectrum (“The Electromagnetic”). Altogether the electromagnetic spectrum comprises of sub regions namely, radio waves, microwaves, infrared waves, visible light, ultraviolet rays, x-rays, and gamma waves. This report discusses in detail about the visible light, infrared rays, x-rays, and ultraviolet rays. Visible light The wavelength of the visible light spectrum ranges from 700 nanometers (nm) to 380 nm. In terms of frequency it is 430 THz to 790 THz (“The Electromagnetic”).This is a very narrow spectral region of the electromagnetic (EM) spectrum which is capable of stimulating the retina of the human eye thus we call it visible light. This visible light region is commonly referred as VIBGYOR that represents the seven colors violet (V), indigo (I), blue (B), green (G), yellow (Y), orange (O), and red (R) (“The Electromagnetic”). Each color is a representative of a unique wavelength and we are capable of perceiving different color sensations when the visible light of that corresponding wavelength strikes the retina of our eye. When light passes through a prism it disperses to form the VIBGYOR band. When our retina is strike by all the wavelengths of visible light at the same time, we perceive white color. The perceived white color is not due to the single color of light but it’s an effect of combination of two or more colors. In technical terms, white is not a single color because there is no wavelength in the visible light spectrum that represents white (“The Electromagnetic”). Actually white is a mixture of colors in the visible spectrum. At the same time it is equally important to discuss about black color. Again in technical terms, black is not a color. Black is actually the nonexistence of wavelengths of the visible light spectrum. Infrared (IR) rays IR rays are one of the sub regions of the EM spectrum whose wavelengths are longer than that of the visible light spectrum. The range of IR rays is from 0.74 µm to 1 mm. In terms of frequency it is 300 GHz to 1 THz (“Infrared Waves”). This range includes most of the thermal radiations emitted by substances at the normal room temperature. When molecules of a substance alter either their vibrational or rotational movements, they produce the IR rays. The IR radiations can be further categorized into three sub regions. They are far-infrared, mid-infrared, and near- infrared regions Far-infrared region ranges from 300 GHz to 30 THz. In terms of wavelength it is 1mm to 10 μm (“Infrared Waves”). The rotational modes exhibited by the molecules in gas phase, the molecular motions exhibited by liquids, and the phonons present in solids absorb the far- infrared radiations. In this frequency range, the water present in the earth’s atmosphere exhibits excellent absorption so that it renders the atmosphere an opaque effect although few wavelengths within this range allows transmission partially. Mid-infrared region ranges from 30 THz to 120 THz. In terms of wavelength, it is 10μm to 2.5 μm (“Infrared Waves”). Hot substances otherwise termed as black-body radiators exhibit excellent emission in this range. When the atoms in the molecules vibrate around their symmetrical position, they absorb the mid-infrared radiations. A compound exhibits a unique absorption radiation pattern in the mid-infrared range so that this range is also known as the ‘fingerprint’ range. The near-infrared region ranges from 120 to 400 THz. In terms of wavelength, it is 2,500 nm to 750 nm (“Infrared Waves”). Physical processes pertinent for the near-infrared range are alike to those for visible light range. Solid state image sensors and photographic films can be used to detect directly, the highest frequencies in the far-infrared region. Another interesting factor regarding the infrared rays is its heating effect for which these IR rays are prevalently known as ‘heat radiations’. Though visible light and other EM radiations also cause heating effect the IR rays solely account for 49% of heating up of the earth’s surface (“Infrared Waves”). The heating effect produced by IR rays can even propagate through vacuum. Although infrared rays are usually referred as ‘heat radiation’, only substances radiating with a particular range of emissivity and temperature would yield maximum of their electromagnetic radiations in the infrared portion of the spectrum (“Infrared Waves”). Approximately 10 microns is the boundary region between the far and the mid infrared regions and human beings, their surroundings, and the earth discharge their thermal radiations around this 10 microns range. If the emissivity of an object is known, its temperature can be determined with the help of infrared radiations. This application of infrared rays is known as thermography and it is much useful in many industrial, meteorological, and military applications. X – Rays The wave length of x- rays ranges from 0.01 nm to 10 nm. In terms of frequency it is 30 petahertz (3×1016 Hz) to 30 exahertz (3×1019 Hz) (“X-rays”). X- rays are generated when the electrons released from a hot cathode rod is accelerated to a very high velocity with the help of a high accelerating potential and the entire process takes place within a vacuum tube also known as x-ray tube. On collision of the accelerated high velocity electrons with a metal target (anode), x-rays are produced. The energy of the generated x-ray photon depends on the energy of the electron incident on the anode (“X-rays”). When the accelerated electron collides with the anode, x-rays are generated by two different kinds of atomic processes described below. If the incident electron has sufficient energy to break the bond of a valence electron out of the inner electron orbit of the metal atom, electrons from the higher energy levels tend to fill up the vacancy and as a result the x-ray photons are released. This process is termed as X-ray fluorescence. X-rays are produced at some distinct frequencies as a spectrum of emissions and this spectral emission is termed as ‘spectral lines’(“X-rays”). Depending on the material which is used as the anode, the characteristics of the spectral lines vary accordingly. “ The other atomic process is Bremsstrahlung, which means braking radiation. When the electrons get scattered by the powerful electric field close to the high proton number nuclei they give off radiations termed as Bremsstrahlung. The x-rays emitted by this process are characterized by a continuous spectrum. The intensity of the x-rays generated and the frequency of the radiation are inversely proportional to each other (“X-rays”). Both the atomic processes exhibit poor production efficiency and in order to improve it, the vacuum tube must be designed in such a way that the heating effect produced due to the consumption of electric power is dissipated properly. Ultraviolet (UV) rays Ultraviolet radiations have wavelengths ranging from 10 nm to 400 nm. We infer from this range that UV rays possess wavelength longer than X-rays but shorter than the visible light. The photon energy range of the UV rays extends from 3 electron volt (eV) to 124 eV (“Ultraviolet Light”). UV rays are invisible to human beings but they are visible to birds and insects. The sunlight comprises of UV radiations and these radiations are capable of producing fluorescence as they undergo several chemical reactions. Though the high energy UV spectrum ranging from 10 nm to 120 nm has certain ionizing effects, most of the UV spectrum is a non-ionizing radiation (“Ultraviolet Light”). Still the UV rays possess certain biological characteristics of the harmful ionizing radiations. This is due to the fact that the photons present in the UV rays have the capability to alter the chemical bonding in biological molecules although they do not have sufficient energy to ionize the atoms present in the molecules. The UV rays can be further classified into three sub regions. They are UV-A ranging from 320 nm to 400 nm, UV-B ranging from 290 nm to 320 nm, and UV-C ranging from 220 nm to 290 nm (“Ultraviolet Light”).They are ordered from smaller to larger energy levels and longer to shorter wavelengths. The most part of UV rays entering the earth’s atmosphere is UV-A as the UV-B and UV-C raysis absorbed by the ozone layer. UV rays can also be categorized as near UV, mid UV, far UV, and extreme UV (“Ultraviolet Light”). Their respective wavelengths are 300-400 nm, 200-300 nm, 200-122 nm, and 121-10 nm (“Ultraviolet Light”). The UV radiations though invisible to human eyes, can cause adverse effects on the skin. The short UV and mid UV are blocked by the ozone layer. If at all they reach the earth’s atmosphere they can cause severe damage to living organisms. The near UV does not cause much damage to the skin yet can damage our skin in long terms and can even cause skin cancer (“Ultraviolet Light”).This does not mean that UV rays are totally harmful as they have beneficial effects too. Exposure to UV-B rays can induce the production of vitamin D in human skin. It helps in the normal functioning of the nervous system by regulating calcium metabolism in the body. It also regulates the immune system, blood pressure, and insulin secretion in the body. So, we have discussed in detail about the various kinds of electromagnetic radiations such as visible light, infrared rays, x-rays, and ultraviolet rays. Works cited “Infrared Waves.” Boundless, 20 Jan 2015. Web. 01 Apr 2015. “The Electromagnetic and Visible Spectra.” Physics class room, n. d. Web. 01 Apr 2015. “Ultraviolet Light.” Boundless, 20 Jan 2015. Web. 01 Apr 2015. “X-Rays.” Boundless, 20 Jan 2015. Web. 01 Apr 2015. Read More