IR课堂练习题
IR习题及答案
IR作业题1.要区别烯醇式和酮式这两种互变异构体可否利用红外光谱？根据什么道理？答：可利用红外光谱区别烯醇式和酮式互变异构体。
因为酮式有两个νC=O吸收峰，而烯醇式则有νC=O和νOH两种吸收峰。
2.已知一化合物的分子式为C10H10O2，推测其结构式可能为：OOH OHOOHO(A) (B) (C)它的IR谱图（稀溶液）在1685cm-1、3360cm-1处有吸收。
你认为哪一种结构式最符合？为什么？答：1685cm-1处为C=O伸缩振动，但比一般的C=O低约20cm-1，这是由于与苯环共轭而使吸收能量降低。
3360cm-1处也比一般的OH伸缩振动低，可能是由于此OH和C=O形成氢键之故，因而最符合的结构式为（A）。
3.指出下列三组吸收峰属于下面哪个化合物。
（1）1865 cm-1和1780 cm-1；（2）1828 cm-1和1750 cm-1；（3）1775 cm-1和1720 cm-1。
C H3COOCH3CO COCOOCH2COOH2C CO(A) (B) (C) 答：吸收峰（1）归属结构(C)吸收峰（2）归属结构(A)吸收峰（3）归属结构(B)4. 某化合物的分子式为C 4H 8O 2，它的红外谱图如下图所示，试推测其结构。
答：该化合物的结构为5. 某化合物的分子式为C 7H 8O ，它的红外谱图如下图所示，试推测其结构。
答：该化合物的结构为CH 3OH CH 3CO OCH 2CH 3。
电路的基本分析方法 练习题及答案第2章
第2章 电路的基本分析方法习题答案2-1 在8个灯泡串联的电路中，除4号灯不亮外其它7个灯都亮。
当把4号灯从灯座上取下后，剩下7个灯仍亮，问电路中有何故障？为什么？解：4号灯灯座短路。
如开路则所有灯泡都不亮。
2-2 额定电压相同、额定功率不等的两个白炽灯能否串联使用，那并联呢？ 解：不能串联使用，因其电阻值不同，串联后分压不同，导致白炽灯无法正常工作。
在给定的电压等于额定电压的前提下，可以并联使用。
2-3 如图2-34所示，R 1=1Ω，R 2=5Ω，U =6V ，试求总电流强度I 以及电阻R 1、R 2上的电压。
图2-34 习题2-3图解：A 151621=++=R R U I=,V 551= V 111=2211=⨯==⨯=IR U IR U2-4 如图2-35所示，R 1=3Ω，R 2=6Ω，U =6V ，试求总电流I ；以及电阻R 1，R 2上的电流。
图2-35 习题2-4图解：总电阻为：Ω263632121=+⨯+=R R R R R=A 326=∴=R U I=由分流公式得：A 13633A 2363621122121=⨯++=⨯++I=R R R =I I=R R R =I2-5 电路如图2-36(a)~(f)所示，求各电路中a 、b 间的等效电阻R ab 。
(a) (b) (c)(d) (e) (f)2-36 习题2-5图解：(a) Ω4.3)6//4()2//2(ab =+=R(b) Ω2)33//()66//4ab =++（=R (c)Ω2)]6//3()6//3//[(13ab =++）（=R(d) Ω2)6//1)6//3(ab =+）（=R (e) Ω7)10//10(}6//6//]2)8//8{[(ab =++=R (f) Ω6}6//]64)4//4{[()4//4(ab =+++=R2-6 求图2-37所示电路中的电流I 和电压U 。
图2-37 习题2-6电路图解：图2-37等效变换可得：由上图可得；Ω8)816//)]}99//(6[5.7{=+++（总=RA 5.1812==总I 则根据并联电路分流作用可得：A 5.05.1)816()]99//(6[5.7)]99//(6[5.7=1=⨯++++++I则A 15.05.1=13=-=-I I I 总 I 3再次分流可得：A 75.0169999=4=⨯+++IA 25.016996=2=⨯++I所以I =0.75A ，U = U +－U － =9×I 2－8×I 1 = 9×0.25－8×0. 5=－1.75V2-7 电路如图2-38(a)~(g)所示，请用电源等效变换的方法进行化简。
IR SC 第二天,灵活做题
例子1：P32页第二题GWD5-Q3:The average hourly wage of television assemblers in Vernland has long been significantly lower than that in neighboring Borodia. Since Borodia dropped all tariffs on Vernlandian televisions three years ago, the number of televisions sold annually in Borodia has not changed. However, recent statistics show a drop in the number of television assemblers in Borodia. Therefore, updated trade statistics will probably indicate that the number of televisions Borodia imports annually from Vernland has increased.Which of the following is an assumption on which the argument depends?A.The number of television assemblers in Vernland has increased by at least as much as thenumber of television assemblers in Borodia has decreased.B.Televisions assembled in Vernland have features that televisions assembled in Borodia donot have.C.The average number of hours it takes a Borodian television assembler to assemble atelevision has not decreased significantly during the past three years.D.The number of televisions assembled annually in Vernland has increased significantly duringthe past three years.E.The difference between the hourly wage of television assemblers in Vernland and the hourlywage of television assemblers in Borodia is likely to decrease in the next few years.例子2:GWD5-Q15:Lightbox, Inc., owns almost all of the movie theaters in Washington County and has announced plans to double the number of movie screens it has in the county within five years. Yet attendance at Lightbox’s theaters is only just large enough for profitability now and the county’s population is not expected to increase over the next ten years. Clearly, therefore, if there is indeed no increase in populati on, Lightbox’s new screens are unlikely to prove profitable.Which of the following, if true about Washington County, most seriously weakens the argument?A.Though little change in the size of the population is expected, a pronounced shift toward ayounger, more affluent, and more entertainment-oriented population is expected to occur.B.The sales of snacks and drinks in its movie theaters account for more of Lightbox’s profitsthan ticket sales do.C.In selecting the mix of movies shown at its theaters, Lightbox’s policy is to avoid those thatappeal to only a small segment of the moviegoing population.D.Spending on video purchases, as well as spending on video rentals, is currently no longerincreasing.E.There are no population centers in the county that are not already served by at least one ofthe movie theaters that Lightbox owns and operates.例子3 39页GWD 5-Q30:Which of the following most logically completes the argument?The irradiation of food kills bacteria and thus retards spoilage. However, it also lowers the nutritional value of many foods. For example, irradiation destroys a significant percentage of whatever vitamin B1 a food may contain. Proponents of irradiation point out that irradiation is no worse in this respect than cooking. However, this fact is either beside the point, since much irradiated food is eaten raw, or else misleading, since _______.A.many of the proponents of irradiation are food distributors who gain from food’s having alonger shelf lifeB.it is clear that killing bacteria that may be present on food is not the only effect thatirradiation hasC.cooking is usually the final step in preparing food for consumption, whereas irradiationserves to ensure a longer shelf life for perishable foodsD.certain kinds of cooking are, in fact, even more destructive of vitamin B1 than carefullycontrolled irradiation isE.for food that is both irradiated and cooked, the reduction of vitamin B1 associated witheither process individually is compounded例子4：GWD5-Q19:Historian: In the Drindian Empire, censuses were conducted annually to determine the population of each village. Village census records for the last half of the 1600’s are remarkably complete.This very completeness makes one point stand out; in five different years, villages overwhelmingly reported significant population declines. Tellingly, each of those five years immediately followed an increase in a certain Drindian tax. This tax, which was assessed on villages, was computed by the central government using the annual census figures. Obviously, whenever the tax went up, villages had an especially powerful economic incentive to minimize the number of people they recorded; and concealing the size of a village’s population from government census takers would have been easy. Therefore, it is reasonable to think that the reported declines did not happen.In the historian’s argument, the two portions in boldface play which of the following roles?A.The first supplies a context for the historian’s argument; the second acknowledges aconsideration that has been used to argue against the position the historian seeks toestablish.B.The first presents evidence to support the position that the historian seeks to establish; thesecond acknowledges a consideration that has been used to argue against that position.C.The first provides a context for certain evidence that supports the position that thehistorian seeks to establish; the second is that position.D.The first is a position for which the historian argues; the second is an assumption thatserves as the basis of that argument.E.The first is an assumption that the historian explicitly makes in arguing for a certain position;the second acknowledges a consideration that calls that assumption into question.例子5：44页20题GWD5-Q38:Nitrogen dioxide is a pollutant emitted by automobiles. Catalytic converters, devices designed to reduce nitrogen dioxide emissions, have been required in all new cars in Donia since 1993, and as a result, nitrogen dioxide emissions have been significantly reduced throughout most of the country. Yet although the proportion of new cars in Donia’s capital city has always been comparatively high, nitrogen dioxide emissions there have showed only an insignificant decline since 1993.Which of the following, if true, most helps to explain the insignificant decline in nitrogen dioxide emissions in Donia’s capital city?A.More of the cars in Donia’s capital city were made before 1993 than after 1993.B.The number of new cars sold per year in Donia has declined slightly since 1993.C.Pollutants other than nitrogen dioxide that are emitted by automobiles have also beensignificantly reduced in Donia since 1993.D.Many Donians who own cars made before 1993 have had catalytic converters installed intheir cars.E.Most car trips in Donia’s capita l city are too short for the catalytic converter to reach itseffective working temperature.例子6，P 50页27题Mayor: Migrating shorebirds stop at our beach just to feed on horseshoe-crab eggs, a phenomenon that attracts tourists. To bring more tourists, the town plans to undertake a beach reclamation project to double the area available to crabs for nesting.Birdwatcher: Without a high density of crabs on a beach, migrating shorebirds will go hungry because shorebirds only eat eggs that a crab happens to uncover when it is digging its own nest. Which of the following, if true, would provide the mayor with the strongest counter to the birdwatcher's objection?A. Every year a certain percentage of crabs are caught by fishermen as bait for eel traps.B. Horseshoe crabs are so prolific that given favorable circumstances their numbers increase rapidly.C. On average, tourists who come to the town in order to watch birds spend more money there than tourists who come for other purposes.D. The additional land made available by the reclamation project will give migrating shorebirds more space.E. Some of the migrating shorebirds make only one stop during their migration from South America to Canada.例子7 P65页第9题Q3:TTGWD11-Q9:The population of desert tortoises in Targland’s Red Desert has declined, partly because they arecaptured for sale as pets and partly because people riding all-terrain vehicles have damaged their habitat. Targland plans to halt this population decline by blocking the current access routes into thedesert and ann ouncing new regulations to allow access only on foot. Targland’s officials predict that these measures will be adequate, since it is difficult to collect the tortoises without a vehicle. Which of the following would it be most important to establish in or der to evaluate the officials’ prediction?A.Whether possessing the tortoises as pets remains legally permissible in TarglandB.Whether Targland is able to enforce the regulations with respect to all-terrain vehicleentry at points other than the current access routesC.Whether the Red Desert tortoises are most active during the day or at nightD.Whether people who travel on foot in the Red Desert often encounter the tortoisesE.Whether the Targland authorities held public hearings before restricting entry byvehicle into the Red Desert例子8P84页Q4~Q6: TTGWD11-Q35 to Q37:Citing the fact that the real grossdomestic product(GDP) per capita was higherin 1997 than ever before, some journalists have argued that the United States economyperformed ideally in 1997. However, the real GDP is almost always higher than ever before; it falls only during recessions. One point these journalists overlooked is that in 1997, as in the twenty-four years immediately preceding it, the real GDP per capita grew nearly one-half percent a year more slowly than it had on average between 1873 and 1973. Were the 1997 economy as robust as claimed, the growth rate of real GDP per capita in 1997 would have surpassed the average growth rate of real GDP per capita between 1873 and 1973 because over fifty percent of the population worked for wages in 1997 whereas only forty percent worked for wages between 1873 and 1973. If the growth rate of labor productivity (output per hour of goods and services) in 1997 had equaled its average growth rate between 1873 and 1973 of more than two percent, then, given the proportionately larger workforce that existed in 1997, real GDP per capita in 1997 would have been higher than it actually was, since output is a major factor in GDP. However, because labor productivity grew by only one percent in 1997, real GDP per capita grew more slowly in 1997 than it had on average between 1873 and 1973.---------------------------------------------------------------- Q4 -- Q35: The passage is primarily concerned withparing various measures used toassess the performance of the UnitedStates economy in 1997B.providing evidence that the performance ofthe United States economy in 1997 wassimilar to its performance between 1873and 1973C.evaluating an argument concerning theperformance of the United States economy in1997D.examining the consequences of a popularmisconception about the performance ofthe United States economy in 1997E.supporting an assertion made byjournalists about the performance of theUnited States economy in 1997-----------------------------------------------------------------Q5 -- Q36: According to the passage, which of the following is true of the average rate at which real GDP per capita grew in the twenty-four years immediately before 1997? A.It was less than it had been between 1873and 1973 because only forty percent of the population worked for wages between1873 and 1973.B.It was less than it had been between 1873and 1973 because labor productivity grewless between 1973 and 1997 than it hadbetween 1873 and 1973.C.It was less than it had been between 1873and 1973 as a result of an increase in thepercentage of the population earningwages during these years.D.It was less than the average rate at whichreal GDP per capita grew between 1873and 1973.E.It was less than the rate at which real GDPper capita grew in 1997.Q6 -- Q37: It can be inferred from thepassage that which of the following is thereason that the author faults the journalistsreferred to in line 4?A.They believe that the real GDP per capita in1997 was higher than the real GDP percapita had ever been before.B.They argue that the rate at which real GDPper capita grew in 1997 was faster than theaverage rate at which it had grownbetween 1873 and 1973.C.They overestimate the effect of laborproductivity on the real GDP per capita in1997.D.They overestimate the amount by whichreal GDP per capita in 1997 surpassed realGDP per capita in earlier years.E.They fail to consider the real GDP per capita in1997 within an appropriate historical context.例子9：GWD-TN-8Prior to 1965 geologists assumed that the two giantrock plates meeting at the San Andreas Fault generate heat through friction as they grind past each other, but in1965 Henry found that temperatures in drill holes near the fault were not as elevated as had been expected. Some geologists wondered whether the absence of friction-generated heat could be explained by the kinds of rock composing the fault. Geologists’ pre-1965 assumptions concerning heat generated in the fault were based on calculations about common varieties of rocks, such as limestone and granite; but “weaker” materials, such as clays, had already been identified in samples retrieved from the fault zone. Under normal conditions, rocks composed of clay produce far less friction than do other rock types. In 1992 Byerlee tested whether these materials would produce friction 10 to 15 kilometers below the Earth’s surface. Byerlee found that when clay samples were subjected to the thousands of atmospheres of pressure they would encounter deep inside the Earth, they produced as much friction as was produced by other rock types. The harder rocks push against each other, the hotter they become; in other words, pressure itself, not only the rocks’ properties, affects frictional heating. Geologists therefore wondered whether the friction between the plates was being reduced by pockets of pressurized water within the fault that push the plates away from each other.例子10 p34页GWD-10-Q4 N-2-Q10 G-10-Q4The passage suggests which of the following regarding Henry’s findings about temperature in the San Andreas Fault?A.Scientists have yet to formulate a definitiveexplanation for Henry’s findings.B.Recent research suggests that Henry’s explanation forthe findings should be modified.C.Henry’s findings had to be recalculated in light ofByerlee’s 1992 experiment.D.Henry’s findings provided support for an assumptionlong held by geologists.E.Scientists have been unable to duplicate Henry’sfindings using more recent experimental methods.-------------------------------------------------------------------GWD-10-Q5 N-2-Q11 G-10-Q5The passage is primarily concerned withA.evaluating a method used to test a particular scientifichypothesisB.discussing explanation for an unexpected scientificfindingC.examining the assumptions underlying a particularexperimentD.questioning the validity of a scientific findingE.presenting evidence to support a recent scientifichypothesis-------------------------------------------------------------------GWD-10-Q6 N-2-Q12 G-10-Q6The passage mostly agree that Henry’s findings about temperature in the San Andreas Fault made the greatest contribution in that theyA.revealed an error in previous measurements oftemperature in the San Andreas Fault zoneB.indicated the types of clay present in the rocks thatform the San Andreas FaultC.established the superiority of a particular technique forevaluating data concerning friction in the San Andreas FaultD.suggested that geologists had inaccurately assumedthat giant rock plates that meet at the San AndreasFault generate heat through frictionE.confirmed geologists’ assumptions about the amountof friction generated by common varieties of rocks,such as limestone and graniteGWD-TN-4GWD6-Q5 to Q7:According to a theory advanced by researcher Paul Martin, the wave of species extinctions that occurred in North America about 11,000 years ago, at the end of the Pleistocene era, can be directly attributed to the arrival of humans, i.e., the Paleoindians, who were ancestors of modern Native Americans. However, anthropologist Shepard Krech points out that large animal species vanished even in areas where there is no evidence to demonstrate that Paleoindians hunted them. Nor were extinctions confined to large animals: small animals, plants, and insects disappeared, presumably not all through human consumption. Krech also contradicts Martin’s exclusion of climatic change as an explanation by asserting that widespread climatic change did indeed occur at the end of the Pleistocene. Still, Krech attributes secondary if not primary responsibility for the extinctions to the Paleoindians, arguing that humans have produced local extinctions elsewhere. But, according to historian Richard White, even the attribution of secondary responsibility may not be supported by the evidence. White observes that Martin’s thesis depends on coinciding dates for the arrival of humans and the decline of large animal species, and Krech, though aware that the dates are controversial, does not challenge them; yet recent archaeological discoveries are providing evidence that the date of human arrival was much earlier than 11,000 years ago.---------------------------------------------------------------------- Q5:Which of the followi ng is true about Martin’s theory, as that theory is described in the passage?A.It assumes that the Paleoindians were primarilydependent on hunting for survival.B.It denies that the Pleistocene species extinctions werecaused by climate change.C.It uses as evidence the fact that humans haveproduced local extinctions in other situations.D.It attempts to address the controversy over the date ofhuman arrival in North America.E.It admits the possibility that factors other than thearrival of humans played a role in the Pleistoceneextinctions.---------------------------------------------------------------------- Q6:Which of the following, if true, would most weaken Krech’s objections to Martin’s theory?A.Further studies showing that the climatic change thatoccurred at the end of the Pleistocene era was evenmore severe and widespread than was previouslybelievedB.New discoveries indicating that Paleoindians made useof the small animals, plants, and insects that became extinctC.Additional evidence indicating that widespread climaticchange occurred not only at the end of the Pleistocene era but also in previous and subsequent erasD.Researchers’ discoveries that many more speciesbecame extinct in North America at the end of thePleistocene era than was previously believedE.New discoveries establishing that both the arrival ofhumans in North America and the wave of Pleistocene extinctions took place much earlier than 11,000 years ago---------------------------------------------------------------------- GWD6-Q7:In the last sentence of the passage, the author refers to “recent archaeological discoveries” (lines 36-37) most probably in order toA.refute White’s suggestion that neither Maritn nor Krechadequately account for Paleoindians’ contributions to the Pleistocene extinctionsB.cast doubt on the possibility that a more definitivetheory regarding the causes of the Pleistoceneextinctions may be forthcomingC.suggest that Martin’s, Krech’s, and White’s theoriesregarding the Pleistocene extinctions are all open toquestionD.call attention to the most controversial aspect of all thecurrent theories regarding the Pleistocene extinctions E.provide support for White’s questioning of bothMartin’s and Krech’s positions regarding the role ofPaleoindians in the Pleistocene extinctions----------------------------------------------------------------------例子11，p 48页Most pre-1990 literature onbusinesses’ use of information technology (IT)—defined as any form of computer-basedinformation system—focused on spectacular IT successes and reflected a general optimism concerning IT’s potential as a resource for creating competitive advantage. But toward the end of the 1980’s, some economists spoke of a “productivity paradox”: despite huge IT investments, most notably in the service sectors, productivity stagnated. In the retail industry, for example, in which IT had been widely adopted during the 1980’s, productivity (average output per hour) rose at an average annual rate of 1.1 percent between 1973 and 1989, compared with 2.4 percent in the preceding 25-year period. Proponents of IT argued that it takes both time and a critical mass of investment for IT to yield benefits, and some suggested that growth figures for the 1990’s proved these benefits were finally being realized. They also argued that measures of productivity ignore what would have happened without investments in IT—productivity gains might have been even lower. There were even claims that IT had improved the performance of the service sector significantly, although macroeconomic measures of productivity did not reflect the improvement.But some observers questioned why, if IT had conferred economic value, it did not produce direct competitive advantages for individual firms. Resource-based theory offers an answer, asserting that, in general, firms gain competitive advantages by accumulating resources that are economically valuable, relatively scarce, and not easily replicated. According to a recent study of retail firms, which confirmed that IT has become pervasive and relatively easy to acquire, IT by itself appeared to have conferred little advantage. In fact, though little evidence of any direct effect was found, the frequent negative correlations between IT and performance suggested that IT had probably weakened some firms’ competitive positions. However, firms’ human resources, in and of themselves, did explain improved performance, and some firms gained IT-related advantages by merging IT with complementary resources, particularly human resources. The findings support the notion, founded in resource-based theory, that competitive advantages do not arise from easily replicated resources, no matter how impressive or economically valuable they may be, but from complex, intangible resources. ----------------------------------------------------------------------GWD5-Q22:The passage is primarily concerned withA.describing a resource and indicatingvarious methods used to study itB.presenting a theory and offering anopposing point of viewC.providing an explanation for unexpectedfindingsD.demonstrating why a particular theory isunfoundedE.resolving a disagreement regarding theuses of a technology----------------------------------------------------------------------GWD5-Q23:The passage suggests that proponents of resource-based theory would be likely to explain IT’s inability to produce direct competitive advantages for individual firms by pointing out thatA.IT is not a resource that is difficult toobtainB.IT is not an economically valuable resourceC.IT is a complex, intangible resourceD.economic progress has resulted from ITonly in the service sectorE.changes brought about by IT cannot bedetected by macroeconomic measures----------------------------------------------------------------------GWD5-Q24:The author of the passage discusses productivity in the retail industry in the first paragraph primarily in order toA.suggest a way in which IT can be used tocreate a competitive advantageB.provide an illustration of the “productivityparadox”C.emphasize the practical value of theintroduction of ITD.cite an industry in which productivity didnot stagnate during the 1980’sE.counter the argument that IT couldpotentially create competitive advantage-----------------------------------------------------------------例子12 P 78页：GWD5-Q25:According to the passage, most pre-1990 literature on businesses’ use of IT included which of the following?A.Recommendations regarding effectiveways to use IT to gain competitiveadvantageB.Explanations of the advantages anddisadvantages of adopting ITrmation about ways in which ITcombined with human resources could beused to increase competitive advantage D. A warning regarding the negative effect oncompetitive advantage that would occur ifIT were not adoptedE. A belief in the likelihood of increasedcompetitive advantage for firms using ITQ33-Q36: TTGWD11-Q24 to Q27:Anole lizard species that occur together(sympatrically) on certain Caribbean islands occupy different habitats: some live only in the grass, some onlyon tree trunks, and some only on twigs. These species also differ morphologically: grass dwellers are slender with long tails, tree dwellers are stocky with long legs, twig dwellers are slender but stubby-legged. What is striking about these lizards is not that coexisting species differ in morphology and habitat use (such differences are common among closely related sympatric species), but that the same three types of habitat specialists occur on each of four islands: Puerto Rico, Cuba, Hispaniola, and Jamaica. Moreover, the Puerto Rican twig species closely resembles the twig species of Cuba, Hispaniola, and Jamaica in morphology, habitat use, and behavior. Likewise, the specialists for other habitats are similar across the islands. The presence of similar species on different islands could be variously explained. An ancestral species might have adapted to exploit a particular ecological niche on one island and then traveled over water to colonize other islands. Or this ancestral species might have evolved at a time when the islands were connected, which some of these islands may once have been. After the islands separated, the isolated lizard populations would have become distinct species while also retaining their ancestors’ niche adaptations. Both of these scenarios imply that specialization to each niche occurred only once. Alternatively, each specialist could have arisen independently on each of the islands.If each type of specialist evolved just once, then similar specialists on different islands would be closely related. Conversely, if the specialists evolved independently on each island, then a specialist on one island would be more closely related to other types of anoles on the same island—regardless of their ecological niches—than it would be to a similar specialist on a different island. Biologists can infer how species are related evolutionarily by comparing DNA sequences for the same genes in different species. Species with similar DNA sequences for these genes are generally more closely related to each other than to species with less-similar DNA sequences. DNA evidence concerning the anoles led researchers to conclude that habitat specialists on one island are not closely related to the same habitat specialists elsewhere, indicating that specialists evolved independently on each island.---------------------------------------------------------------------- 33. The primary purpose of the passage is toA.describe some unusual features of anole lizard speciesB.account for a particular type of behavior found amonganole lizard speciesC.contrast two types of evidence that have been used tosupport a particular hypothesis concerning anole lizard speciesD.explain how researchers resolved a particular scientificquestion concerning anole lizard speciesE.examine different explanations for a particular traitcommon to certain anole lizard species-------------------------------------------------------------34. Which of the following best describes the purpose of the sentence in lines 13-23 (“What is … Jamaica”)?A.It raises a question about why coexisting anole lizardspecies occupy the different types of habitatsmentioned in the first sentence.B.It introduces a fact about anole lizard species that thepassage will go on to explore.C.It identifies a particular aspect of anole lizard behaviorthat distinguishes anoles from other lizard species. D.It explains why one aspect of anole lizard species’habitat use has been difficult to account for.E.It points out a surprising relationship betweenmorphology and habitat use that is explained in theconcluding paragraph.-------------------------------------------------------------------- 35. It can be inferred form the passage that which of the following is true of the Cuban tree-dwelling anole lizard and the Jamaican tree-dwelling anole lizard?A.They share a morphology characterized by stockybodies and long legs.B.They have bodies that are relatively slender comparedto their stubby legs.C.They differ significantly form one another in size.D.They differ significantly from one another in behaviorand habitat use.E.They are genetically closely related to one another.--------------------------------------------------------------------。
IR习题
IR光谱习题一、基本概念题1.红外光谱不仅包括振动能级的跃迁,也包括转动能级的跃迁,故又称为振转光谱。
( )2.同核双原子分子N≡N,Cl—Cl,H一H等无红外活性。
( )35.对称结构分子,如H20分子,没有红外活性,水分子的H—0— H对称伸缩振动不产生吸收蜂。
( )4.红外光谱图中,不同化合物中相同基团的特征频率峰总是在特定波长范围内出现,故可以根据红外光谱图中的特征频率峰来确定化合物中该基团的存在。
( )5.不考虑其他因素的影响,下列羰基化合物νC=O伸缩频率的大小顺序为:酰卤>酰胺>酸>醛>酯。
( )6.红外光谱与紫外光谱仪在构造上的差别是检测器不同。
( )7.当分子受到红外光激发,其振动能级发生跃迁时,化学键越强吸收的光子数目越多。
()8.游离有机酸C=O伸缩振动νC=O 频率一般出现在1760cm-1,但形成多聚体时,吸收频率会向高波数移动。
( )9.醛、酮、羧酸等的羰基( >C=O )的伸缩振动在红外光谱中的吸收峰频率相同。
()10.红外光可引起物质的能级跃迁是( )。
A.分子的电子能级的跃迁,振动能级的跃迁,转动能级的跃迁;B.分子内层电子能级的跃迁;C.分子振动能级及转动能级的跃迁;D.分子转动能级的跃迁。
11.某化合物在紫外光区270nm处有一弱吸收,在红外光谱中有如下吸收峰:2700~2900cm-1, 1725cm-1, 则该化合物可能是( )。
A. 醛;B. 酮;C. 羧酸;D. 酯。
12. 下列两个化合物的红外光谱有何不同?二、谱图分析题1. 某化合物其可能的结构为A或B, 试根据如下部分红外光谱图确定其结构。
2. 某化合物含有C、H、O, 根据如下红外谱图回答下面问题:(l) 该化合物是脂肪族还是芳香族? (2) 是否为醇类化合物? (3) 是否为醛、酮、酸、酯类化合物?(4) 是否含有双键或三键? (5) 综合以上问题给出该化合物可能的类型。
(完整版)基尔霍夫定律练习题
基尔霍夫定律 一.填空题1.能应用 电路和 电路 的规律进行分析和计算的电路,叫简单电路.这种电路可用 定律进行分析和计算.不能应用 电路和 电路的规律进行分析和计算的电路叫复杂电路,适用此电路重要定律是 .2.三个或三个以上电流的汇聚点叫.两个节点间的任一电流所经过的路径叫 .电路中从某一节点出发,任意绕行回到原出发点的闭合路径叫 .最简单的回路叫 .任何一个独立的回路中,必须至少包含一条其它 中没有用过的新 .3. 基尔霍夫第一定律也叫 定律 ,可用字母 表示.其数学表达式Σ.I=0含义是:进某一 的全部电流之和恒等于零;数学表达式ΣI 入=ΣI 出的含义是:进入某一节点的全部电流之际 恒等于流出该节点的全部电流之 .4. 基尔霍夫第二定律也叫 定律 ,可用字母 表示.其数学表达式.ΣU=0含义是:沿回路绕行一周,沿途各部分 的 恒等于零;数学表达式ΣE=ΣIR 的含义:沿回路绕行一周,沿途各电动势的 恒等于沿途各 两端电压的 .5.应用基尔霍夫定律列节点电流方程时,若电路中有n 个节点,就可以列出 个 的节点电流方程,若电路 中有m 条支路,应该列出 个 的回路电压方程.6.如果某复杂电路有3个节点,3个子网孔,5条支路,要采用支路电流法求解各支路电流共应列出其 个方程.其中,节点电流方程 个,回路电压方程 个.7. 基尔霍定律是进行电路 和 的 的最 的定律.它适合于 电路.8.如图.有 个节点,其中独立的节点 个,有 条支路;有 个回路,有网孔.9.如图,应用支路电流法求解的五个方程应是.(1) (2) (3) （４） （５） ．１０．电路中各点的电位都是 ，参考点而言的．如果事先没有指 ，谈电路中某点电位就毫无意义了．在计算电路中某点电位时，必须首先确定该电路的 ．电位的高低与计算时绕行 和参考点的 有关，而与绕行的 无关．二．选择题Ａ直流电路Ｂ交流电路Ｃ简单电路Ｄ．复杂电路Ｅ．线性电路Ｆ．非线性电路 ２．如图．为某一电路中的一个节点，则Ｉ４是（ ）３．如图，Ｅ１＝１０Ｖ，Ｅ２＝２５Ｖ，Ｒ１＝５Ω，Ｒ２＝10Ω,I=3A,则I 1与I 2分别是( ) A.1A,2A B.2A,1A C.3A,0A D.0A, 3A4.如图,E 1=12V,E 2=9V ,R 1=R 6=1Ω,R 2=0.5Ω,R 3=5Ω,R 4=6Ω,R 5=3Ω,则A,B 两点电位( ) A.V A >V B ,B,V A <V B .C.V A =V B D.V A —V B =0I1 10A I2 5A I3 -5A I45.当电路开路时,电源的电动势与电源的端电压( )A.大小相等,方向相反B.同一物理量 C 大小相等,方向相反 D.大小不等,方向相反 6.如图,两个网络A,B 之间用一根导线a 相连.则导线a 中的电流强度i( ) A.一定为零B 一定不为零C 不一定为零也可能为零,要视具体情况而定 7.KCL 定律适用于:( )A.电路 中的节点B.电路中任一假定封闭面C.电路中的网孔,回路D 电路中的任一假想回路 8.有一电流表Rg=1000Ω,Ig=100uA,现要改装成量程为了1A 的安培表,可用( )方法,若要改装成量程为了1V 的伏特表,可用( )的方法A.并联,10Ω电阻B 串联,0.1Ω电阻C 并联,0.1Ω电阻D.串联,9K Ω电阻 9.下列说法中,正确的说法有:( )A. 基尔霍夫电流定律可推广应用于电路中任意一个假 想封闭面B.ΣI=0,正负号与事先标定的各支路,电流的正负号是一致的C, 基尔霍夫电压定律应用于电路中任一闭合路径,且这一路径可以是开路的. 10.进行电路分析的最基本定律是( )A.叠加原理B 戴维南定理C.欧姆定律D, 基尔霍夫定律 11.在使用基尔霍夫定律ΣE=ΣIR 时,( )A.应首先设定电流表正方向B.沿回路绕行方向可以作选C.E 的方向与绕行方向一致时,E 取正值D.I 的方向与绕向一致时,IR 取正值 12.如图,节点数和支路数分别为( ) A.2 B.3 C.4 D.5三.计算题1.如图.已知R 1=2Ω,R 2=3Ω.R 3=5Ω,R 4=4Ω.E 1=36V ,E 2=16V ,E 3=12V ,各电源的内阻均忽略不计,令e 点为参考点,求(1)各点的电位和ad 两点间的电压Uad.(2)若改f 点为参考点,求其它各点的电位及ad 两点间的电压Uad.2.如图.已知I=20mA,I 2=8mA,I 4=15mA,求其余各电阻中的电流.E1R2fcb3.如图,已知I 1=5mA,,I 2=16mA,I 3=8mA,I 4=6mA,R 1=3K Ω,R 2=2K Ω,R 3=5K Ω,R 4=10K Ω,E 2=6V ,求(1)E 1为多少,(2)求Uab.4.如图,已知R 1=R 2=R 3=R 4=10Ω,E 1=12V ,E 2=9V,E 3=18V,E 4=3V ,求用基尔霍夫定律求回路中的电流及E,A 两端的电压?5.如图,利用基尔霍夫电压定律列方程6.如图,电流的参考方向如图,已知I 1=4A,I 2=7A,I 4=10A,I 5=25A,求I 3,I 6E1R2E1R3E1E3E2feR4b aR3R4R5R1R2R3R4E2I1I2I3I4abc d E1E2R1R2R3ABI1I2I34R1E17.如图,已知E 1=20V ,E 2=4V ,R 1=10Ω,R 2=2Ω,R 4=3Ω,8.如图.当开关S 断开和闭合时,a 点电位各为多少?9.如图,已知,U 1=12V ,U 2=-6V ,R 1=R 2=20K Ω,R 3=10K Ω,求a 点的电位及各电阻中的电流.aR3R1R2Va a。
基尔霍夫定律练习题
基尔霍夫定律 一.填空题1.能应用 电路和 电路 的规律进行分析和计算的电路,叫简单电路.这种电路可用 定律进行分析和计算.不能应用 电路和 电路的规律进行分析和计算的电路叫复杂电路,适用此电路重要定律是 .2.三个或三个以上电流的汇聚点叫 .两个 节点间的任一电流所经过的路径叫 .电路中从某一节点出发,任意绕行回到原出发点的闭合路径叫 .最简单的回路叫 .任何一个独立的回路中,必须至少包含一条其它 中没有用过的新 .3. 基尔霍夫第一定律也叫 定律 ,可用字母 表示.其数学表达式Σ.I=0含义是:进某一 的全部电流之和恒等于零;数学表达式ΣI 入=ΣI 出的含义是:进入某一节点的全部电流之际 恒等于流出该节点的全部电流之 .4. 基尔霍夫第二定律也叫 定律 ,可用字母 表示.其数学表达式.ΣU=0含义是:沿回路绕行一周,沿途各部分 的 恒等于零;数学表达式ΣE=ΣIR 的含义:沿回路绕行一周,沿途各电动势的 恒等于沿途各 两端电压的 .5.应用基尔霍夫定律列节点电流方程时,若电路中有n 个节点,就可以列出 个 的节点电流方程,若电路 中有m 条支路,应该列出 个 的回路电压方程.6.如果某复杂电路有3个节点,3个子网孔,5条支路,要采用支路电流法求解各支路电流共应列出其 个方程.其中,节点电流方程 个,回路电压方程 个.7. 基尔霍定律是进行电路 和 的 的最 的定律.它适合于 电路.8.如图.有 个节点,其中独立的节点 个,有 条支路;有 个回路,有网孔.9.如图,应用支路电流法求解的五个方程应是.(1) (2) (3) （４） （５） ．１０．电路中各点的电位都是 ，参考点而言的．如果事先没有指 ，谈电路中某点电位就毫无意义了．在计算电路中某点电位时，必须首先确定该电路的 ．电位的高低与计算时绕行 和参考点的 有关，而与绕行的 无关．二．选择题Ａ直流电路Ｂ交流电路Ｃ简单电路Ｄ．复杂电路Ｅ．线性电路Ｆ．非线性电路 ２．如图．为某一电路中的一个节点，则Ｉ４是（ ）３．如图，Ｅ１＝１０Ｖ，Ｅ２＝２５Ｖ，Ｒ１＝５Ω，Ｒ２＝10Ω,I=3A,则I 1与I 2分别是( ) A.1A,2AB.2A,1AC.3A,0AD.0A, 3A4.如图,E 1=12V,E 2=9V,R 1=R 6=1Ω,R 2=Ω,R 3=5Ω,R 4=6Ω,R 5=3Ω,则A,B 两点电位() >V B ,B,V A < —V B =0I1 10A I2 5A I3 -5A I45.当电路开路时,电源的电动势与电源的端电压( )A.大小相等,方向相反B.同一物理量 C 大小相等,方向相反 D.大小不等,方向相反 6.如图,两个网络A,B 之间用一根导线a 相连.则导线a 中的电流强度i( ) A.一定为零B 一定不为零C 不一定为零也可能为零,要视具体情况而定 定律适用于:( )A.电路 中的节点B.电路中任一假定封闭面C.电路中的网孔,回路D 电路中的任一假想回路 8.有一电流表Rg=1000Ω,Ig=100uA,现要改装成量程为了1A 的安培表,可用( )方法,若要改装成量程为了1V 的伏特表,可用( )的方法A.并联,10Ω电阻B 串联,Ω电阻C 并联,Ω电阻D.串联,9K Ω电阻 9.下列说法中,正确的说法有:( )A. 基尔霍夫电流定律可推广应用于电路中任意一个假 想封闭面B.ΣI=0,正负号与事先标定的各支路,电流的正负号是一致的C, 基尔霍夫电压定律应用于电路中任一闭合路径,且这一路径可以是开路的. 10.进行电路分析的最基本定律是( )A.叠加原理B 戴维南定理C.欧姆定律D, 基尔霍夫定律 11.在使用基尔霍夫定律ΣE=ΣIR 时,( )A.应首先设定电流表正方向B.沿回路绕行方向可以作选 的方向与绕行方向一致时,E 取正值 的方向与绕向一致时,IR 取正值 12.如图,节点数和支路数分别为( ) .3 C三.计算题1.如图.已知R 1=2Ω,R 2=3Ω.R 3=5Ω,R 4=4Ω.E 1=36V,E 2=16V,E 3=12V,各电源的内阻均忽略不计,令e 点为参考点,求(1)各点的电位和ad 两点间的电压Uad.(2)若改f 点为参考点,求其它各点的电位及ad 两点间的电压Uad.2.如图.已知I=20mA,I 2=8mA,I 4=15mA,求其余各电阻中的电流.E1R2fcb3.如图,已知I 1=5mA,,I 2=16mA,I 3=8mA,I 4=6mA,R 1=3K Ω,R 2=2K Ω,R 3=5K Ω,R 4=10K Ω,E 2=6V,求(1)E 1为多少,(2)求Uab.4.如图,已知R 1=R 2=R 3=R 4=10Ω,E 1=12V,E 2=9V,E 3=18V,E 4=3V,求用基尔霍夫定律求回路中的电流及E,A 两端的电压5.如图,利用基尔霍夫电压定律列方程6.如图,电流的参考方向如图,已知I 1=4A,I 2=7A,I 4=10A,I 5=25A,求I 3,I 6E1R2E1R3E1E3E2feR4b aR3R4R5R1R2R3R4E2I1I2I3I4abc d E1E2R1R2R3ABI1I2I34R1E17.如图,已知E 1=20V,E 2=4V,R 1=10Ω,R 2=2Ω,R 4=3Ω,8.如图.当开关S 断开和闭合时,a 点电位各为多少9.如图,已知,U 1=12V,U 2=-6V,R 1=R 2=20K Ω,R 3=10K Ω,求a 点的电位及各电阻中的电流.aR3R1R2Va a。
【精选】基尔霍夫定律练习题
基尔霍夫定律一.填空题1.能应用 电路和 电路 的规律进行分析和计算的电路,叫简单电路.这种电路可用 定律进行分析和计算.不能应用 电路和 电路的规律进行分析和计算的电路叫复杂电路,适用此电路重要定律是 .2.三个或三个以上电流的汇聚点叫 .两个 节点间的任一电流所经过的路径叫 .电路中从某一节点出发,任意绕行回到原出发点的闭合路径叫 .最简单的回路叫 .任何一个独立的回路中,必须至少包含一条其它 中没有用过的新 .3. 基尔霍夫第一定律也叫 定律 ,可用字母 表示.其数学表达式Σ.I=0含义是:进某一 的全部电流之和恒等于零;数学表达式ΣI 入=ΣI 出的含义是:进入某一节点的全部电流之际 恒等于流出该节点的全部电流之 .4. 基尔霍夫第二定律也叫 定律 ,可用字母 表示.其数学表达式.ΣU=0含义是:沿回路绕行一周,沿途各部分 的 恒等于零;数学表达式ΣE=ΣIR 的含义:沿回路绕行一周,沿途各电动势的 恒等于沿途各 两端电压的 .5.应用基尔霍夫定律列节点电流方程时,若电路中有n 个节点,就可以列出 个 的节点电流方程,若电路 中有m 条支路,应该列出 个 的回路电压方程.6.如果某复杂电路有3个节点,3个子网孔,5条支路,要采用支路电流法求解各支路电流共应列出其 个方程.其中,节点电流方程 个,回路电压方程 个.7. 基尔霍定律是进行电路 和 的 的最 的定律.它适合于 电路.8.如图.有 个节点,其中独立的节点 个,有 条支路;有 个回路,有网孔.9.如图,应用支路电流法求解的五个方程应是.(1) (2) (3) （４） （５） ．１０．电路中各点的电位都是 ，参考点而言的．如果事先没有指 ，谈电路中某点电位就毫无意义了．在计算电路中某点电位时，必须首先确定该电路的 ．电位的高低与计算时绕行 和参考点的 有关，而与绕行的 无关．二．选择题Ａ直流电路Ｂ交流电路Ｃ简单电路Ｄ．复杂电路Ｅ．线性电路Ｆ．非线性电路 ２．如图．为某一电路中的一个节点，则Ｉ４是（ ）３．如图，Ｅ１＝１０Ｖ，Ｅ２＝２５Ｖ，Ｒ１＝５Ω，Ｒ２＝10Ω,I=3A,则I 1与I 2分别是( ) A.1A,2AB.2A,1AC.3A,0AD.0A, 3A4.如图,E 1=12V,E 2=9V ,R 1=R 6=1Ω,R 2=0.5Ω,R 3=5Ω,R 4=6Ω,R 5=3Ω,则A,B 两点电位()A.V A >V B ,B,V A <V B .C.V A =V B D.V A —V B =0I1 10A I2 5A I3 -5A I45.当电路开路时,电源的电动势与电源的端电压( )A.大小相等,方向相反B.同一物理量 C 大小相等,方向相反 D.大小不等,方向相反 6.如图,两个网络A,B 之间用一根导线a 相连.则导线a 中的电流强度i( ) A.一定为零B 一定不为零C 不一定为零也可能为零,要视具体情况而定 7.KCL 定律适用于:( )A.电路 中的节点B.电路中任一假定封闭面C.电路中的网孔,回路D 电路中的任一假想回路 8.有一电流表Rg=1000Ω,Ig=100uA,现要改装成量程为了1A 的安培表,可用( )方法,若要改装成量程为了1V 的伏特表,可用( )的方法A.并联,10Ω电阻B 串联,0.1Ω电阻C 并联,0.1Ω电阻D.串联,9K Ω电阻 9.下列说法中,正确的说法有:( )A. 基尔霍夫电流定律可推广应用于电路中任意一个假 想封闭面B.ΣI=0,正负号与事先标定的各支路,电流的正负号是一致的C, 基尔霍夫电压定律应用于电路中任一闭合路径,且这一路径可以是开路的. 10.进行电路分析的最基本定律是( )A.叠加原理B 戴维南定理C.欧姆定律D, 基尔霍夫定律 11.在使用基尔霍夫定律ΣE=ΣIR 时,( )A.应首先设定电流表正方向B.沿回路绕行方向可以作选C.E 的方向与绕行方向一致时,E 取正值D.I 的方向与绕向一致时,IR 取正值 12.如图,节点数和支路数分别为( ) A.2 B.3 C.4 D.5三.计算题1.如图.已知R 1=2Ω,R 2=3Ω.R 3=5Ω,R 4=4Ω.E 1=36V ,E 2=16V ,E 3=12V ,各电源的内阻均忽略不计,令e 点为参考点,求(1)各点的电位和ad 两点间的电压Uad.(2)若改f 点为参考点,求其它各点的电位及ad 两点间的电压Uad.2.如图.已知I=20mA,I 2=8mA,I 4=15mA,求其余各电阻中的电流.E1R2fcb3.如图,已知I 1=5mA,,I 2=16mA,I 3=8mA,I 4=6mA,R 1=3K Ω,R 2=2K Ω,R 3=5K Ω,R 4=10K Ω,E 2=6V ,求(1)E 1为多少,(2)求Uab.4.如图,已知R 1=R 2=R 3=R 4=10Ω,E 1=12V ,E 2=9V,E 3=18V,E 4=3V ,求用基尔霍夫定律求回路中的电流及E,A 两端的电压?5.如图,利用基尔霍夫电压定律列方程6.如图,电流的参考方向如图,已知I 1=4A,I 2=7A,I 4=10A,I 5=25A,求I 3,I 6E1R2E1R3E1E3E2feR4b aR3R4R5R1R2R3R4E2I1I2I3I4abc d E1E2R1R2R3ABI1I2I34R1E17.如图,已知E 1=20V ,E 2=4V ,R 1=10Ω,R 2=2Ω,R 4=3Ω,8.如图.当开关S 断开和闭合时,a 点电位各为多少?9.如图,已知,U 1=12V ,U 2=-6V ,R 1=R 2=20K Ω,R 3=10K Ω,求a 点的电位及各电阻中的电流.aR3R1R2Va a。
焦耳定律练习题(含答案)
焦耳定律练习题(含答案)焦耳定律练习题一、填空题1、电热毯是冬季北方常用的取暖设备，它是利用________来工作的。
而计算机内都装有小风扇，它工作时把热空气驱走，这是为了________。
2、某加热装置的工作原理如图所示，两电阻丝的阻值相等，电源电压不变，它有加热和保温两个工作状态。
当开关S1接b，S2断开时，它是处于状态，此时电路功率为P1；当开关S1接a，S2闭合时，电路功率为P2，则P1∶P2＝。
3、小刚用如图甲所示电路来探究电流与电压的关系，闭合开关S，将滑动变阻器的滑片P从a端移至b端，电流表和电压表的示数变化关系如图乙所示，由图像可得，定值电阻R1的阻值是Ω．实验时，电源电压保持5V不变，当滑片P位于a端时，滑动变阻器消耗的电功率是＿＿＿ W，此时，电阻R1在10min内产生的热量为 ______J二、选择题4、一只“220V 45W”的电烙铁，在额定电压下使用，每分钟产生的热量是( )A、45JB、220JC、2700J D、9900J4、如图1所示，额定功率为2W的小灯泡Ｌ与一个阻值为4Ω的电阻Ｒ串联后接到电压为6V的电源上，小灯泡恰能正常发光。
则通电1分钟，小灯泡产生的热量是（）Ａ．80J Ｂ．120J Ｃ．540J Ｄ．无法判断5、家用电吹风由电动机和电热丝等组成，为了保证电吹风的安全使用，要求：电动机不工作时，电热丝不能发热；电热丝发热和不发热时，电动机都能正常工作。
如下图所示电路中符合要求的是（）6、电流通过导体时导体会发热，根据这个道理可制成（）A．电风扇 B．电铃 C．电炉 D．发电机7、一台电动机正常工作时线圈两端的电压为380V，线圈电阻为2，线圈中电流为10A。
这台电动机正常工作1S消耗的电能为W，产生的热量为Q，则（）A．W=3800J，Q=200J B．W=3800J，Q=3800J C．W=72200J，Q=200J D．W=72200J，Q=3800J8、有两根阻值分别为的电阻丝，分别采用下图所示的四种方法接在同一电源上后，相同时间内产生的热量最大的是（）9、一个电炉接在220V的电路上时用10min可以烧开一壶水，若该接在110V的电路上（忽略散热等因素影响），烧开这壶水需要的时间为（）A．10min B．20min C ．30min D ．40min10、小洁家购买了一台电饭锅，在使用时闻到橡胶的焦糊味，用手摸其电源线发现很热，而其它用电器仍正常工作，请你用所学的物理知识帮小洁分析一下，发生这一现象的原因是（）A.电压太高B.导线太粗C.导线太细D.导线太短11、在家庭电路中，导线相互连接处往往比别处更容易发热，老化更快。