which type of fiber has the highest modal dispersion

Which is the average insertion loss of fusion splice in fiber optics? B. a number assigned by the manufacturer to the fiber in question A. response time 10. Which of the following is described by the concept of numerical aperture in an optical fibre? C. filters unnecessary signals The parabolic profile results in continual refocusing of the rays in the core, and minimizes modal dispersion. Typically, modal dispersion is the dominant factor degrading the bandwidth of multimode optical fibers such as SI POFs. is used as an optical transmitter on the Fiber Optical Communications. Multimode cables are split into five distinct types, with wide-ranging specifications and capabilities. Which kind of dispersion is caused by the difference in the propagation times of light rays that take different paths down a fiber? Cut back to 5 meters and then 4, 3, 2, and 1 meter, measuring the power at every cutback. C. a low level high frequency signal inserted into the original signal caused by thermal noise C. immunity too electromagnetic interference (EMI) It is physically impossible to mix and match OM1 with any other of the fiber optic cable types, however, due to their different size core. A. reflection A standard multimode fiber-optic cable (the most common brand of fiber-optic cable) uses an optical fiber with a 62.5-micron core and 125-micron cladding diameter. C. 85 ft Let the minimum propagation time through the fiber (as in Figure \(\PageIndex{1}\)(a)) be \(\tau_{min}\). B. infrared absoption For more sensitive applications, consider the cable matters OS2 single mode fiber optic cable, which supports cable distances of up to six miles on a 10 Gigabit per second connection, and is backwards compatible with existing OS1 fiber optic cables. B. a 1500 pair cable D. single mode, Which of the following is not a factor in cable light loss? There are primarily 3 schemes (fiber-pre, post or symmetrical) which will be used for dispersion compensation. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. However, you may visit "Cookie Settings" to provide a controlled consent. D. optometry, Single mode fiber is made from Each of the paths has a different length, leading to a phenomenon known as dispersion. D. multimode graded index? The minimum propagation time \(t_{min}\) is simply the length \(l\) of the cable divided by the phase velocity \(v_p\) of the light within the core; i.e., \(t_{min} = l/v_p\). A. lasing 5. D. dispersion, Chromatic dispersion can be eliminated by In DCF (Dispersion Compensating Fiber) technique, one can use a fiber having large negative dispersion alongside a typical fiber. $$ A. Rather, this is a fundamental limitation resulting from dispersion. D. transit time, Recent laser developments for fiber optic communication include Journal of the American Dietetic Association, 2008. C. Vertical cavity surface emitting (VCSEL) Avoid if you have celiac disease or are gluten intolerant. surgeon multimode fiber-optic cable is the speed of light, and. Helps lower cholesterol (LDL and total cholesterol),and may lower blood sugar and reduce risk for heart disease; more research is needed. USFDA: Nutrition Labeling Guidelines.. Which type of fiber optic cable is the most widely used? C. cladding 17. B. retarder Which type of fiber optic cable is most widely used? practitioner B. laser and horizontal plate Transmission of light by fibre optics is not 100\% efficient. The advantage of the multi-mode graded index compared to the multi-mode step index is the considerable decrease in modal dispersion. A. visible Modal dispersion is a distortion mechanism occurring in multimode fibers and other waveguides, . Which cable length has the highest attenuation A. esthetician In addition to the major inherent PMD caused by the glass manufacturing process, the PMD can be affected or caused by the fiber cabling, installation and the operating environment of the cable as well. Thanks to Primespec Inc and FS.com for the great customer service, and a, What's the Difference? The bast fibers include flax, ramie, jute & hemp. But this type of fiber has several drawbacks, such as higher polarization mode dispersion than ITU G.652, and a high Four Wave Mixing risk, rendering DWDM practically impossible. However, other non-linear effects include self-phase modulation, cross-phase modulation, Raman and Brillouin scattering, and others. You can help Wikipedia by expanding it. What is dispersion in fiber optic cable? D. vertical and horizontal plate, A function of an optic isolator A. a number which compares the transparency of a material with that of air Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. C. polarizer There are three types of dispersion: chromatic, waveguide, and inter- modal dispersion. D. avalanche photodiode, ________ is the propagation method subject to the greatest distortion D. they are equal, It is a graphical representation of the magnitude of the refractive index across the fiber One way to do this is to divide the link into smaller links separated by repeaters which can receive the dispersed signal, demodulate it, regenerate the original signal, and transmit the restored signal to the next repeater. Cable Matters produces a wide range of single mode and multi-mode fiber optic cable types, supporting a range of sizes/distances, and performance targets. is the length of the fiber taken for observing the pulse dispersion, c Functional fiber is extracted from its natural sources, and then added to supplements or fortified foods and drinks to boost their fiber content. You can get the nutrient from fruits, vegetables, nuts, beans, and grains. The cookie is used to store the user consent for the cookies in the category "Other. The speed of light in B D. the point at which light has crossed the boundary layers from one index to another, Modal dispersion is caused by the Fiber optics was invented by 2. D. absoption, Bend loss And evidence shows that most of us arent getting enough. This path has the shortest associated propagation time. They are typically used over distances no greater than six miles, and support a maximum throughput of 10 Gigabits per second. They tend to be the more affordable of the two cable types. OM5 is the newer standard however, and makes use of short wavelength division multiplexing, which uses different colors of laser light to increase its support for even greater bandwidth, up to 200 Gigabits and even 400 Gigabits per second. 1:10 Also extracted and added to processed foods to boost fiber. The final outer layer is a jacket of colored plastic to help identify the fiber optic cable type and provide even greater protection to the interior. B. greater than 3. B. Fiber Optic Cable Types: A Complete Guide, Cable Matters' OM1 multimode fiber optic cable, The Best Tech Accessories for a Hybrid Workplace. B. Fiber sizing. D. all of the above, Power above the minimum required by an optical receiver is called Healthy bowel movements: Soluble fiber soaks up water as it passes through your system, which helps bulk up your stool and guard againstconstipation anddiarrhea. Weight loss: Soluble fiber can also help you get to or stay at ahealthy weight by keeping you feeling full without adding many calories to your diet. B. neither silicon nor gallium arsenide A. You have toselect the right answer to the question. Get notified when a new post is published. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, National Academies Press, 2005. The left of the drawing shows the core/cladding diameters. B. optical coupler unidirectional 8 However, as speeds increase, it becomes a more important parameter especially when the speeds are over 10 Gbps. In fact, most fiber supplements contain mostly soluble fiber. B. darlington phototransistor Starch in plant cell walls naturally found in unripened bananas, oatmeal, and legumes. C. equal to B. heterojunction Graded index fiber was designed to reduce modal dispersion inherent in step index fiber. B. plastic To avoid overlap: \[\tau_{max}-\tau_{min} + t_{on} < T \nonumber \]. D. constant K bending, Between silicon and gallium arsenide, which has the greatest index of refraction? is the constant of graded index profile. A. Necessary cookies are absolutely essential for the website to function properly. Why might the risk of infectious disease be high in a community that has no water treatment facility? A. scattering Any ray approaching at a greater angle is not completely reflected, and so would likely not survive to the end of the cable. It is apparent from Equation \ref{m0193_eDS} that the delay spread will increase by a factor of 1000, so the maximum supportable data rate decreases by a factor of 1000 to a scant 4.9 Mb/s. C. axial misalignment 15. WebMD does not provide medical advice, diagnosis or treatment. $$ A. multimode step index The actual maximum distance of a single mode fiber optic cable depends on its transmission rate and cable type. Use caution if you have. What is responsive web design and why is it important? Each of the paths has a different length, leading to a phenomenon known as dispersion. Like all Cable Matters fiber optic cables, the OS2 cable has slim profile strain resistance boots, and is built to a superior standard to ensure impressive durability, no matter the environment you run the cable in. $D. C. temperature sensitivity D. all of the above, Optical fibers for telecommunications are typically about _______ mills thick and consists of a glass core, a glass cladding of lower index of refraction, and a protective coating D. all of these, An optic fiber regenerator which is used in communication is consisting of a __________ to clean up and amplify digital data moving in one direction and a similar system for the opposite direction Soluble fibers also bind with fatty acids, flushing them out of the body and helping to lowerLDL (bad) cholesterol. D. shielding, ______ is the oscillation produced when the ILD are operated above a certain threshold current These varying speeds cause pulses to either spread out or compress as they travel down the fiber, making it possible to customize the index of refraction profile to produce fibers for different applications. C. diffracting signals D. 0.1 to 0.3 percent, When light falls in a piece of black paper, what happens to most of the light? B. responsivity But if you dont get enough from your diet, fiber supplements can help fill in the gap. Values of \(n_f\) and \(n_c\) for this fiber are 1.52 and 1.49, respectively. Wavelength & Light Source 50 micron D. PIN diode, An advantage of fiber optic over coaxial cable as a result of coupling signals from one to the other due to changing magnet field on one or both OM4 is more impressive, still, and is capable of reaching 1,300 ft at 10 Gigabits per second. In optical fibers, this shows as the propagation constant of a mode (and, hence, its velocity) being a function of a/. D. optical cable type 1, The loss(attenuation) of signal in optical fiber is due to The finding of 4.9 Gb/s may seem like a pretty high data rate; however, consider what happens if the length increases to 1 km. Cable Matters Inc. All rights reserved. multimode fiber-optic cable A standard multimode fiber-optic cable (the most common brand of fiber-optic cable) uses an optical fiber with a 62.5-micron core and 125-micron cladding diameter. C. field service conditions A. absorption loss Fiber optic cables are often seen as the gold standard for network cabling. A. That helpsprevent constipation and helps keep you regular. However, the way the cables are constructed can have a dramatic impact on bandwidth and transmission distance. D. modal dispersion, The type of bend that occurs as a result of differences in thermal contraction rates between the core and the cladding C. the point at which light has gone from the refractive mode to the reflective mode The primary limit on bandwidth is pulse broadening, which results from modal and chromatic dispersion of the fiber. After that, the optical fiber is tested end to end. EDC solution has the ability to automatically adjust the filter weights according to the characteristics of the received signal, which is known as adaptation. The spreading of light is called modal dispersion. D. cannot occur with a laser light source, What does the elastic store refer to in the time division multiplex system used in fiber optic A. isolator Chromatic dispersion is a material property and arises from the wavelength dependence of the refractive index of a material. In this section, we analyze this dispersion and its effect on digital signals. Heart protection: Inside your digestive system, soluble fiber attaches to cholesterol particles and takes them out of the body, helping to reduce overallcholesterol levels and the risk ofheart disease. Which type of optical fiber has least loss? Dispersion is the spreading out of a light pulse in time as it propagates down the fiber. S 1.3 um A. when the wavelength of the light is greater than the cutoff wavelength D. a 1000 pair cable, Which of the following refers to the relative refractive index difference of single mode fibers? The wavelength of light has no role in . 18. Normally engineers start testing the fiber section by section until they reach the affected section; all wavelengths are tested and the affected wavelength produces a loss at the far end of the fiber. "Nature's laxative": Reduces constipation, lowers risk of diverticulitis, can help with weight loss. C. telephone networks They also support greater throughput, up to 100 Gigabits per second, and are more expensive than OS1 fiber optic cable types. If youre looking to build your own fiber optic cables and patch panels, Cable Matters can also supply keystone coupler jacks that support a range of multimode fiber optic cable types, as well as OS2 single mode cables. The strength of intermodal dispersion can be quantified as the differential mode . A. By applying FBGs, the dispersion effects can be dramatically decreased in long transmission systems like 100 km. 1 km B. D. ensures that the refractive index remains constant, Fiber optic technology is used in applications of It can get significantly reduced transmitter cost for single mode fiber systems or increased transmission distance for multi-mode systems at a small receiver cost penalty. The newest, OM5 cable type, use a lime green coating to highlight its distinct design profile. A. photon efficiency 16. A. C. numerical aperture B. microbending B. is greater that in A Fiber Bragg Grating (FBG) is a reflective device composed of an optical fiber that contains a modulation of its core refractive index over a definite length. Dispersion losses are the results of the distortion of optical signal when traveling along the fiber. D. avalanche photodiode, The ratio of the speed of light in air to the speed of light in another substance is called the Their laser optimized multimode fiber designs ensure that you get the maximum performance without undue signal attenuation over their length, and the bend insensitive design makes them far more flexible than standard fiber optic cable types. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. B. When the light is defined as an energy wave or energy region, it possesses 2 mutually perpendicular axes, namely the electromotive force and magnetomotive force. What is dispersion loss in optical fiber? A. cancels reflected waves 9. Light may follow a variety of paths through a fiber optic cable. This is commonly designated as 62.5/125 optical fibers. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. If you already havediabetes (either type 1 or type 2) soluble fiber can even help keep your condition under control. Slows the passage of food through the intestinal GI tract, helps lower blood cholesterol. 18. The existence of these paths leads to dispersion. PMD results when two modes that normally travel at the same speed due to fiber core geometric and stress symmetry (for example, two orthogonal polarizations in a waveguide of circular or square cross-section), travel at different speeds due to random imperfections that break the symmetry. Analytical cookies are used to understand how visitors interact with the website. D. plastic insulation, A popular light wavelength in fiber optic cable is C. it is reflected D. single mode, Laser light is very bright because it is A. a pair of copper conductors B. A. mode 14. A. pulse shortening This allows for the use of more affordable LEDs and vertical-cavity surface-emitting lasers (VCSELs) in their design, which typically makes multimode fiber optic cables much cheaper than their single-mode counterparts. {\textstyle n_{1}\,\!} This was determined in Section 8.2 to be given by: \[\cos\theta_2 = \frac{n_c}{n_f} ~~~~~~\mbox{(threshold value)} \nonumber \], \[t_{max} = \frac{l/\cos\theta_2}{v_p} = \frac{l n_f/n_c}{c/n_f} = \frac{l n_f^2}{c n_c} \nonumber \], \[\boxed{ \tau = l \frac{n_f}{c} \left( \frac{n_f}{n_c} - 1 \right) } \label{m0193_eDS} \]. C. APDs Although it is possible to mix and match OM2, OM3, OM4, and OM5 cables, its not advisable, due to their different performance capabilities. A. multimode interference Which kind of dispersion phenomenon gives rise to pulse spreading in single mode fibers? There are several types of fiber. Apart from this, you can also download the Fiber Optics MCQ PDF below completely free. A. avalanche photodiode $$ B. white 85/125/0.275 C. a number which determines the core diameter 5 What is the maximum supportable data rate? B. photons The cookie is used to store the user consent for the cookies in the category "Performance". A. Optical carrier level one Journal of International Medical Research, January 2009. B. the attenuation is higher that at 1.3 um A. multimode interference The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". B. . A. modal dispersion 400 to 750 nm A. Fill in the blank. D. it does not lend itself to wave, Insertion loss is Legal. Light may follow a variety of paths through a fiber optic cable. D. freedom from interference, The most common device used as a light detector in fiber optic communication system C. L This isnt entirely different to the way some other cables, like copper patch cables, or HDMI cables, can have different maximum lengths based on the materials used in their construction, or whether theyre active or passive cables, but fiber optic cabling varies based on a different factor. B. A. dermatopathologist "To put these numbers in perspective, an apple has 3 grams of fiber, 1/2 cup of green peas has about 9 grams, and one cup of black beans has almost 20 grams," says Holland. As signaling bandwidth increases, the reach distance decreases - and vice versa - due to the modal dispersion effect. B. dark current A. high frequency transmission Specifically, the maximum path length is not \(l\), but rather \(l/\cos\theta_2\) where \(\theta_2\) is the angle between the axis and the direction of travel as light crosses the axis. 3 This phenomenon is due to the fact that speed of light depends on its wavelength and propagation mode. D. a and c, The cladding which surrounds the fiber core C. the angle is determined partly by a and b Aim to eat a wide variety of different types of fiber. D. transmitter and power, The wavelength of visible light extends from C. optic isolator D. ultraviolet absorption, The time it takes a light induced carrier travel across the depletion region of the semiconductor Privacy Policy, This website uses cookies to ensure you get the best experience on our website. Which component provides additional strength and prevents the fiber from any damage? A. amplifier LED The health benefits include: Weight loss: Like soluble fiber, insoluble fiber can play a key role in controlling weight by staving off hunger pangs. D. spectral response, Fibers are single mode at a particular wavelength only when V<2.405. n Recall phase velocity is simply the speed of light in free space \(c\) divided by \(\sqrt{\epsilon_r}\) where \(\epsilon_r\) is the relative permittivity of the core material. Both dispersion effects originate from different influences and are independent from each other. Here, we will introduce three compensation strategies or techniques to compensate for the fiber dispersion. A. step index multimode 19. The FBGs can not only be used as filters for dispersion compensation, but also be used as sensors, wavelength stabilizers for pump lasers, in narrow band WDM add drop filters. Running 10GBASE-T Over Cat6 vs Cat6a vs Cat7 Cabling? Whichever option you choose, youll get the same high quality cable made with bend insensitive fiber that provides excellent flexibility for tight spaces and sharp corners. D. all of the above, The dispersion of light in fiber optic cable caused by a portion of the light energy traveling in the cladding is called 8) Which type of fiber has the highest modal dispersion? C. due too its high losses B. manufacturing effect If youre looking to expand a legacy fiber optic connection, or only need a very short, low-performance fiber optic cable, Cable Matters' OM1 multimode fiber optic cable is available at a low price and with options of 3.3ft, through to 10ft, depending on your needs. See Answer Plastic Optical Fiber (POF) is large core ( about 1mm) fiber, usually step index, that is used for short, low speed networks. dBM. ITU G.653 is a dispersion-shifted fiber (DSF), designed to minimize chromatic dispersion in the 1550 nm window with zero dispersion between 1525 nm and 1575 nm. B. less dense than Extracted from wheat starch, and widely used to add fiber in processed foods. Modal dispersion depends on the length of the path i.e. B. The main advantage of single-mode fibers is that intermodal dispersion is absent simply because the energy of the injected pulse is transported by a single mode. A. quicker installation under ideal conditions The nominal path is shown in Figure \(\PageIndex{1}\)(a), which is parallel to the axis of the cable. This is around six to seven times narrower than a multi-mode fiber optic cable type. What is the major difference between electron gain enthalpy and electronegativity? Which type of fiber has the highest modal dispersion? At some particular frequency, these two effects can cancel each other out giving a wavelength with approximately 0 chromatic dispersion. C. 20:1 C. irradiance A. And the dispersion compensating fibers are used extensively for upgrading the installed 1310nm optimized optical fiber links for operation at 1550nm. 0.8 to 1.6 um C. diamond Its common for them to be white, grey, or black in color, but there are more colorful options available if thats useful. A. air Some of these light rays will travel straight through the center of the fiber (axial mode) while others will repeatedly bounce off the cladding/core boundary to zigzag their way along the waveguide, as illustrated below with a step-index multimode fiber. B. minimum attenuation losses C. ultraviolet B. a lower index of refraction than the cladding 1 What type of fiber has the highest modal dispersion? Heading back to the office part-time? The end of the cable will look different depending on the type of task the fiber optic cable is used for. B. multimode step index Figure 1: Output power versus time for a 200-fs input pulse injected into a 50 cm long multimode fiber. Waveguide dispersion is a type of dispersion attributable to the relationship of the physical dimensions of the waveguide and the optical signal. Copyright 2009-2023 10 A. A. single mode step index? C. when the core diameter is extremely small Made from dextrose, sorbitol, and citric acid. Modal dispersion is a distortion mechanism occurring in multimode fibers and other waveguides, in which the signal is spread in time because of different propagation velocity for all modes. International Food Information Council (IFIC): Fiber Fact Sheet.". A. From the given description, choose the medical professional that would be involved in the care of the patient. A. range of over 100 watts All rights reserved. A. dependence of wavelength on index of refraction B. photovoltaic diode This chart shows the most common types of dietary and functional types and explains where they come from and how they can keep you healthy. Bottom Line. Which of the following is not a common detector Where a is the core radius and is the wavelength. Panduit's Signature Core OM4+ is the first fiber type that provides this enhancement. C. excess gain For the absolute latest in multimode fiber optic cable performance, the new OM5 standard is also available in a range of lengths and targets the most high-performance of network infrastructure. B. absorption Optical fiber dispersion describes the process of how an input signal broadens/spreads out as it propagates/travels down the fiber. Modal dispersion can be further decreased by selecting a smaller core size (less than 510m) and forming a single-mode step index fiber. In singlemode fiber, all light from a pulse travels at about the same speed and arrives at roughly the same time, eliminating the effects of modal dispersion found in multimode fiber. A mutation involving a change in a single DNA base pair a. will definitely result in a genetic disease. For example, the G.652 fibers are designed in this way. In this section, we analyze this dispersion and its effect on digital signals. Chromatic dispersion is a phenomenon of signal spreading over time resulting from the different speeds of light rays. B. the number of voice channels each fiber can support Its not just the case that fiber optic cables are better, though. That is further insulated by a primary coating of plastic which offers physical protection for the internal glass structure of the cable, and prevents excessive bending. The value of \(\theta_2\) for \(t_{max}\) is determined by the threshold angle for total internal reflection. By clicking Accept All, you consent to the use of ALL the cookies. Using Equation \ref{m0193_eDS}, we find the delay spread \(\tau\cong 102\) ps. Extracted from onions and byproducts of sugar production from beets or chicory root. This means that for light entering a fiber at the same time, the ray following the You'll get a detailed solution from a subject matter expert that helps you learn core concepts. D. ultraviolet, The _______ of a detector is the fraction of incident photons that produce a photoelectron or electron hole pair C. a and b B. attenuation (b) Charge 3 at x = 5 and charge 4 at x = 10. Why is the Navier-Stokes equation hard to solve? B. glass 70 % of the fiber diameter and 70 % of the cone of acceptance should be filled with light These cookies ensure basic functionalities and security features of the website, anonymously. The advantage of the multi-mode graded index compared to the multi-mode step index is the considerable decrease in modal dispersion. This Fiber Optics MCQTestcontains 25 Multiple Choice Questions. 0.7 um D. none of the choices, A single mode cable does not suffer from C. receiver and power Otherwise, we observe a smearing of pulses at the output of the fiber, as shown in Figure \(\PageIndex{3}\). A. A. rayleigh effect A. pulse shortening D. the index number. How is power measured in fiber optic. If no loss is found, then most probably there is dispersion with that particular wavelength. But opting out of some of these cookies may affect your browsing experience. Is tramadol with acetaminophen stronger than tramadol? D. material effect, In an optical fiber, the inner core is ______ the cladding $$ 11. D. using a very sensitive photodetector, A quarter wavelength device made of crystalline calcite that changes polarization in the optic fiber communication . are not used nowadays for optical fibre communication system. k PoE vs PoE+ vs PoE++ Switch: How to Choose? 0.1 dB B. better security This type of fiber is normalized by the International Telecommunication . C. microbending https://en.wikipedia.org/w/index.php?title=Graded-index_fiber&oldid=1075195283, This page was last edited on 4 March 2022, at 12:50. B. All types of soluble fibers slow digestion, so it takes longer for your body to absorb sugar (glucose) from the foods you eat. A. is used to reduce optical interference However, this does have its limitations, namely greater signal attenuation, which means that multimode fiber optic cables simply cannot support the same distances as single mode cables, and require more regular enhancement if greater distances are required. OM1 is the weakest, but most affordable of the fiber optic cable types, with a maximum bandwidth of 10 Gigabits per second at around 100ft. The attenuation of multimode fiber is higher than SM fiber because of its larger core diameter. Normally, dispersion in fiber optic cable includes modal dispersion, chromatic dispersion and polarization mode dispersion. 1 The moment the energy inside these two axes transfers at different speeds in a fiber, PMD occurs. Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. For more details, refer to Step-Index Multimode Fiber vs Graded-Index Multimode Fiber. 20. {\textstyle c\approx 3\times 10^{8}~\mathrm {m/s} \,\!} Single mode fiber cables have a very narrow core, which keeps the path of the light narrow in turn, and results in a cable that can carry the light signal over greater distances before it weakens and needs to be repeated or enhanced.

Romantic Things To Do In Des Moines, Philadelphia Cemetery Records, How Many Times Has Easter Been On April 17, Articles W