McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Uncategorized topics .
| 151. |
Multimode graded index fibers with wavelength of 0.85μm have numerical aperture of 0.29 have core/cladding diameter of |
| A. | 62.5 μm/125 μm |
| B. | 100 μm/140 μm |
| C. | 85 μm/125 μm |
| D. | 50 μm/125μm |
| Answer» B. 100 μm/140 μm | |
| Explanation: multimode graded index fibers with numerical aperture 0.29 having a core/cladding diameter of 100μm/140μm. | |
| 152. |
Multimode graded index fibers use incoherent source only. |
| A. | true |
| B. | false |
| Answer» B. false | |
| Explanation: multimode graded index fibers are used for short haul and medium to high bandwidth applications. small haul applications require leds and low accuracy lasers. thus either incoherent or incoherent sources like led’s or injection laser diode are used. | |
| 153. |
In single mode fibers, which is the most beneficial index profile? |
| A. | step index |
| B. | graded index |
| C. | step and graded index |
| D. | coaxial cable |
| Answer» B. graded index | |
| Explanation: in single mode fibers, graded index profile is more beneficial as compared to step index. this is because graded index profile provides dispersion-modified-single mode fibers. | |
| 154. |
The fibers mostly not used nowadays for optical fiber communication system are |
| A. | single mode fibers |
| B. | multimode step fibers |
| C. | coaxial cables |
| D. | multimode graded index fibers |
| Answer» A. single mode fibers | |
| Explanation: single mode fibers are used to produce polarization maintaining fibers which make them expensive. also the alternative to them are multimode fibers which are complex but accurate. so, single-mode fibers are not generally utilized in optical fiber communication. | |
| 155. |
Single mode fibers allow single mode propagation; the cladding diameter must be at least |
| A. | twice the core diameter |
| B. | thrice the core diameter |
| C. | five times the core diameter |
| D. | ten times the core diameter |
| Answer» D. ten times the core diameter | |
| Explanation: the cladding diameter in single mode fiber must be ten times the core diameter. larger ratios contribute to accurate propagation of light. these dimension ratios must be there so as to avoid losses from the vanishing fields. | |
| 156. |
A fiber which is referred as non- dispersive shifted fiber is? |
| A. | coaxial cables |
| B. | standard single mode fibers |
| C. | standard multimode fibers |
| D. | non zero dispersion shifted fibers |
| Answer» B. standard single mode fibers | |
| Explanation: a standard single mode fiber having step index profile is known as non- dispersion shifted fiber. as these fibers have a zero dispersion wavelength of 1.31μm and so are preferred for single-wavelength transmission in o-band. | |
| 157. |
Standard single mode fibers (SSMF) are utilized mainly for operation in |
| A. | c-band |
| B. | l-band |
| C. | o-band |
| D. | c-band and l-band |
| Answer» C. o-band | |
| Explanation: ssmfs are utilized for operation in o-band only. it shows high dispersion in the range of 16 to 20ps/nm/km in c-band and l-band. so ssmfs are used in o-band. | |
| 158. |
Fiber mostly suited in single-wavelength transmission in O-band is? |
| A. | low-water-peak non dispersion-shifted fibers |
| B. | standard single mode fibers |
| C. | low minimized fibers |
| D. | non-zero-dispersion-shifted fibers |
| Answer» B. standard single mode fibers | |
| Explanation: standard single mode fibers with a step index profile are called non dispersion shifted fiber and it is particularly used for single wavelength transmission in o- band and as if has a zero-dispersion wavelength at 1.31μm. | |
| 159. |
Fluoride glass is used with |
| A. | ir waves |
| B. | uv rays |
| C. | normal light |
| D. | all of the mentioned |
| Answer» A. ir waves | |
| Explanation: flouride glass is suitable for ir rays of wavelength upto 3200 nm. | |
| 160. |
Silica glass of hydroxyl concentration can be used for of wavelength. |
| A. | 100 nm to 250 nm |
| B. | 250 nm to 800 nm |
| C. | 800 nm to 1500 nm |
| D. | 100 nm to 3400 nm |
| Answer» B. 250 nm to 800 nm | |
| Explanation: silica glass with hydroxyl concentration is used for wavelength 250 nm to 800 nm. | |
| 161. |
OTDR stands for |
| A. | optical time domain reflectometer |
| B. | optical transfer data rate |
| C. | optical time data registers |
| D. | none of the mentioned |
| Answer» A. optical time domain reflectometer | |
| Explanation: otdr is the short form of optical time domain reflectometer. | |
| 162. |
Which of the following is not correct for fibre optic sensors? |
| A. | immune to electro magnetic interference |
| B. | immune to radiation hazard |
| C. | can be used in harsh environments |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| Explanation: all of the mentioned are qualities of fibre optic sensors. | |
| 163. |
Epoxy material in fibre optics is intended for |
| A. | better optical properties |
| B. | better reflection |
| C. | better sealing |
| D. | reducing noise |
| Answer» C. better sealing | |
| Explanation: polished epoxy seal provides liquid and air tight seal. | |
| 164. |
Plastics optical cables can be used for |
| A. | short range |
| B. | medium range of distance |
| C. | long range of distance |
| D. | very high range of distance |
| Answer» A. short range | |
| Explanation: plastic optical cables are manufacturing for short range purposes. | |
| 165. |
Which of the following represents loss associated with glass fibres? |
| A. | 3 db/km |
| B. | 10 db/km |
| C. | 0 db/km |
| D. | 50 db/km |
| Answer» A. 3 db/km | |
| Explanation: glass fibres have a net loss of 3 db on every single kilometre. | |
| 166. |
Loss associated with plastic fibre is less than glass fibres. |
| A. | true |
| B. | false |
| Answer» B. false | |
| Explanation: loss associated with plastic fibre is about 100-1250 db/km and it is several times larger than glass fibres. | |
| 167. |
Cladding in glass fibre have high refractive index than the core. |
| A. | true |
| B. | false |
| Answer» B. false | |
| Explanation: cladding in glass fibre is always kept at a low refractive index than the core. | |
| 168. |
The transfer of heat between two bodies in direct contact is called |
| A. | radiation |
| B. | convection |
| C. | conduction |
| D. | none of the mentioned |
| Answer» C. conduction | |
| Explanation: this is the definition of conduction. | |
| 169. |
In the equation, dQ=TdX |
| A. | dq is an inexact differential |
| B. | dx is an exact differential |
| C. | x is an extensive property |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: this is because heat transfer is a path function. | |
| 170. |
The transfer of heat between a wall and a fluid system in motion is called |
| A. | radiation |
| B. | convection |
| C. | conduction |
| D. | none of the mentioned |
| Answer» B. convection | |
| Explanation: this is the definition of convection. | |
| 171. |
The specific heat of the substance is defined as the amount of heat required to raise a unit mass of the substance through a unit rise in temperature. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: c=q/(m*Δt). | |
| 172. |
Heat and work are |
| A. | path functions |
| B. | inexact differentials |
| C. | depend upon the path followed |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: it is an important point to remember regarding heat and work transfer. | |
| 173. |
Latent heat is taken at |
| A. | constant temperature |
| B. | constant pressure |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| Explanation: the latent heat is heat transfer required to cause a phase change in a unit mass of substance at a constant pressure and temperature. | |
| 174. |
Which of the following is true? |
| A. | latent heat of fusion is not much affected by pressure |
| B. | latent heat of vaporization is highly sensitive to pressure |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| Explanation: it is a general fact about latent | |
| 175. |
Heat transfer and work transfer are |
| A. | boundary phenomena |
| B. | energy interactions |
| C. | energy in the transit |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: it is an important point to remember regarding heat and work transfer. | |
| 176. |
A faulty thermometer has its fixed points marked as 5° and 95°. The temperature of a body as measured by the faulty thermometer is 59°. Find the correct temperature of the body on a Celsius scale. |
| A. | 60°c |
| B. | 40°c |
| C. | 20°c |
| D. | 0°c |
| Answer» A. 60°c | |
| Explanation: (tc-0)/(100-0)=(temperature on faulty scale-lower fixed point)/(upper fixed point-lower fixed point) | |
| 177. |
Temperature is a microscopic concept. |
| A. | true |
| B. | false |
| Answer» B. false | |
| Explanation: temperature is a macroscopic concept. it is related to the average kinetic energy of a large number of molecules forming a system. it is not possible to define the temperature for a single molecule. | |
| 178. |
2 THERMAL EXPANSION OF SOLIDS AND LIQUIDS |
| A. | high heat capacity |
| B. | no heat capacity |
| C. | small heat capacity |
| D. | varying heat capacity |
| Answer» C. small heat capacity | |
| Explanation: the thermometer bulb having small heat capacity will absorb less heat from the body whose temperature is to be measured. hence the temperature of that body will practically remain unchanged. | |
| 179. |
Calorie is defined as the amount of heat required to raise the temperature of 1g of water by 1°C and it is defined under which of the following conditions? |
| A. | from 14.5°c to 15.5°c at 760mm of hg |
| B. | from 98.5°c to 99.5°c at 760mm of hg |
| C. | from 13.5°c to 14.5°c at 76mm of hg |
| D. | from 3.5°c to 4.5°c at 76mm of hg |
| Answer» A. from 14.5°c to 15.5°c at 760mm of hg | |
| Explanation: one calorie is defined as the heat required to raise the temperature of 1g of water from 14.5°c to 15.5° at 760mm of hg. | |
| 180. |
Compared to burn due to air at 100°C, a burn due to steam at 100°C is |
| A. | more dangerous |
| B. | less dangerous |
| C. | equally dangerous |
| D. | not dangerous |
| Answer» A. more dangerous | |
| Explanation: compared to burn due to air at 100°c, a burn due to steam at 100°c is more dangerous due to the additional heat possessed by steam. | |
| 181. |
540g of ice at 0°C is mixed with 540g of water at 80°C. What is the final temperature of the mixture? |
| A. | 0°c |
| B. | 40°c |
| C. | 80°c |
| D. | less than 0°c |
| Answer» A. 0°c | |
| Explanation: heat gained by ice = heat lost by water at 80°c 540×80+540×1×θ=540×1×(80-θ) | |
| 182. |
If the sun were to increase in temperature from T to 2T and its radius from R to 2R, then the ratio of the radiant energy received on earth to what it was previously, will be |
| A. | 4 |
| B. | 16 |
| C. | 32 |
| D. | 64 |
| Answer» D. 64 | |
| Explanation: energy radiated by the sun per second, | |
| 183. |
On a hilly region, water boils at 95°C. What is the temperature expressed in Fahrenheit? |
| A. | 100°f |
| B. | 203°f |
| C. | 150°f |
| D. | 20.3°f |
| Answer» B. 203°f | |
| Explanation: (f-32)/9=c/5=95/5 f = 171+32 = 203°f. | |
| 184. |
Temperatures of two stars are in ratio 3:2. If wavelength of maximum intensity of first body is 4000 Å, what is corresponding wavelength of second body? |
| A. | 9000 Å |
| B. | 6000 Å |
| C. | 2000 Å |
| D. | 8000 Å |
| Answer» B. 6000 Å | |
| Explanation: ((ʎm)‘)/ʎm = t/t‘ = 3/2 | |
| 185. |
Identify the given joint in Concrete Structures. |
| A. | horizontal construction joint |
| B. | vertical construction joint |
| C. | expansion construction joint |
| D. | water tank joint |
| Answer» A. horizontal construction joint | |
| Explanation: the construction joints are provided at locations were the construction is | |
| 186. |
Identify the given joint in Concrete Structures. |
| A. | horizontal construction joint |
| B. | expansion construction joint |
| C. | vertical construction joint |
| D. | water tank joint |
| Answer» C. vertical construction joint | |
| Explanation: the construction joint maybe horizontal or vertical. for an inclined or curved member of the joint should be at right angle to the axis of the member. it is necessary to determine the location of construction joints well in advance for the viewpoint of structural stability. | |
| 187. |
Identify the given type of joint in Concrete Structures. |
| A. | l beam construction joint |
| B. | t beam construction joint |
| C. | expansion joint |
| D. | contraction joint |
| Answer» B. t beam construction joint | |
| Explanation: in case of t-beams, the ribs should be filled with concrete first and in the slabs forming the flanges can be filled up to the centre of the ribs. if a construction joint between slab and beam becomes unavoidable | |
| 188. |
Identify the given joint in Concrete Structures. |
| A. | expansion joint |
| B. | contraction joint |
| C. | water tank joint |
| D. | vertical construction joint |
| Answer» C. water tank joint | |
| Explanation: for water tanks and other structured which store water, the strips of copper, aluminium, galvanized iron or other corrosion resistant material known as water stops or waterbars, are placed in construction joint as shown in given figure above. | |
| 189. |
Identify the given joint in Concrete Structures. |
| A. | partial contraction joint |
| B. | complete contraction joint |
| C. | horizontal construction joint |
| D. | dummy joint |
| Answer» D. dummy joint | |
| Explanation: above figure shows another form of contraction joint. it is also known as a dummy joint and in this case, a groove of 3 mm width is created in the concrete member to act as a joint. the groove is filled with the joint filler and its depth is about 1/3 to 1/5 of the total thickness of the member. | |
| 190. |
For water tanks and other structure which store water, the strips of copper, aluminium, galvanized iron or other collision resistance material, known as the |
| A. | joints |
| B. | waterstops |
| C. | dowels |
| D. | fillers |
| Answer» B. waterstops | |
| Explanation: the function of waterstops is to seal the joint against the passage of water. | |
| 191. |
The expansion and contraction joints generally consist of some elastic material, known as which should be compressible, rigid, cellular and Resilient. |
| A. | keys |
| B. | joint filler |
| C. | keys |
| D. | fillers |
| Answer» B. joint filler | |
| Explanation: the usual joint filler are built- in strips of metal, bitumen treated felt, cane fibre board, cork bound with rubber or resin, dehydrated cork, natural cork, softwood free from knots, etc. | |
| 192. |
The are provided in expansion and contraction joints to transfer the load. |
| A. | dowels |
| B. | fillers |
| C. | joint filler |
| D. | waterbars |
| Answer» A. dowels | |
| Explanation: the contraction joints are installed to allow for shrinkage movement in the structure. it may either be a complete contraction joint or a partial construction joint. in the former case, there is complete discontinuity of both concrete and steel. | |
| 193. |
The is a mixture of cement and sand, the usual proportion being 1:3. |
| A. | mortar |
| B. | slurry |
| C. | gunite |
| D. | concrete |
| Answer» C. gunite | |
| Explanation: a cement gun is used to deposit the gunite mixture on the concrete surface under pressure of about 20 n/cm2 to 30 n/cm2. the cement is mixed with slightly moist sand and the necessary water is added as the mixture comes out from the cement gun. | |
| 194. |
Measurement of elevated temperatures is defined as |
| A. | thermometry |
| B. | pyrometry |
| C. | metallography |
| D. | radiography |
| Answer» B. pyrometry | |
| Explanation: pyrometry deals with elevated temperatures, generally around 950 f. the apparatus that is used in this process is known as a pyrometer. thermometry generally deals with the measurement of temperatures below 950 f. | |
| 195. |
What temperature is the dark orange color associated with? |
| A. | 1475 f |
| B. | 1650 f |
| C. | 1750 f |
| D. | 1800 f |
| Answer» B. 1650 f | |
| Explanation: temperature of metals can be estimated by simply looking at the color of the hot body. dark orange is associated with a temperature of about 1150 f, while for bright cherry, orange, and yellow it is 1475 f, 1750 f, and 1800 f correspondingly. | |
| 196. |
Bimetallic strips contain as a metal. |
| A. | muntz metal |
| B. | yellow brass |
| C. | bronze |
| D. | aluminum |
| Answer» B. yellow brass | |
| Explanation: bimetallic strips include invar as one metal and yellow brass as another. for higher temperatures, nickel alloy can be used. these can be used in temperatures ranging from -100 f to 1000 f. | |
| 197. |
Why is invar used in bimetallic strips? |
| A. | low density |
| B. | low coefficient of expansion |
| C. | high-temperature resistance |
| D. | high abrasion resistance |
| Answer» B. low coefficient of expansion | |
| Explanation: most bimetallic strips are composed of invar and yellow brass as metal. invar has the advantage of low coefficient of expansion, whereas yellow brass has the ability to be used at low temperatures. | |
| 198. |
is commonly used in liquid- expansion thermometers. |
| A. | bourdon tube |
| B. | spinning rotor gauge |
| C. | mcleod gauge |
| D. | manometer |
| Answer» A. bourdon tube | |
| Explanation: liquid-expansion thermometers consist of a bulb and an expansible device. | |
| 199. |
Resistance thermometer generally makes use of for the measurement of resistance. |
| A. | potentiometer |
| B. | adruino |
| C. | diode bridge |
| D. | wheatstone bridge |
| Answer» D. wheatstone bridge | |
| Explanation: resistance thermometers are based on the principle of increase in electrical resistance with increasing temperature. it consists of a resistance coil mounted in a protecting tube which is connected to a resistance measuring instrument. generally, wheatstone bridge is used in this process. | |
| 200. |
Which of these materials is not used for resistance coils? |
| A. | nickel |
| B. | copper |
| C. | titanium |
| D. | platinum |
| Answer» C. titanium | |
| Explanation: resistance coils are generally made of nickel, copper, or platinum. nickel and copper can be used in the temperature range of 150-500 f, whereas platinum can be used between -350 to 1100 f. | |
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