电工电子技术模拟题（一）

1、电工电子技术模拟题（一）一、 填空题(每空2分，共20分) 1 任意时刻，流入电路中任一（节点）的电流之和恒等于（流出）该节点的电流之和。2 放大电路的信号源内电阻（RS）越高，电路的电压放大倍数（越小）。3对于TTL门电路， 1. 输出为（高电位）时，带负载的能力弱。输出为（低电位）时，带负载的能力强。4.磁力线越密表示磁场（越强）。5描述逻辑功能的方法有： （真值表）、（逻辑图）、（表达式）。二、 单项选择题（每题4分，共20分） 1、图1所示电路中U为（ A ）。2A - 45V + A. 30V U 15 B. -10V 图1 C. -40V 2、图2所示电路中，电源电压不变，而频率升

2、高，各灯泡的亮度变化是（ B ）。C B A u A. 灯泡A变亮 L C R B. 灯泡B变亮 图2 C. 灯泡C变亮 3、图3所示变压器，已知原方N1=300匝， R=8，则从原方看入的电阻Ri是72，则变压器副方绕组N2为（ C ）。A.200匝 B.300匝 C. 100匝 N2 N1 Ri 图3 R 4、稳压二极管是利用其工作在（ C ）时电压变化极小的特性，使两端电压得到稳定的。A. 正向 B.反向 C. 反向击穿 5、放大电路引入电压并联负反馈，可以使输入电阻（ B ）。A. 增大 B.减小 C. 不变 三、 计算题（每题15分，共30分） 1图3-1所示电路可用来测量电源的数值

3、及其内阻，图中标出的U和R0组成某实际电压源。已知R1=2.6，R2=5.5，当开关K1闭合，K2打开时，电流表读数为2A；打开K1，闭合K2后，读数为1A，试求U和R0。 R2 R1 R0 图3-1 U K2 K1 解：K1闭合，K2打开，有 I1（R0+R1）=U K1打开，K2闭合，有 I2（R0+R2）=U 联立上两式，得出 U=5.8V， R0=0.3 2、有一电感线圈，当接在电压为40V的直流电源上时，测得线圈电流为4A。当接于电压为220V、频率为50HZ的正弦交流电源时，测得电流为10A，求线圈电阻与电感。解：直流电源作用时 XL=L=0，R=40/4=10 交流电源作用时 Z

4、=22 XL=19.6 L=62.4mH 四、 简答题（每题5分，共30分） 1、恒压源的性质是什么？ 恒压源的性质为（1）它的输出电压始终是恒定的，不受输出电流的影响；（2）通过它的电流不由它本身决定，由与之相连的负载电阻决定。2、简述RLC串联电路产生串联谐振的特点？ （1）电路的阻抗最小并呈电阻性。（2）电路中的电流最大。（3）XL=XC，串联谐振可在电容和电感两端产生高电压。3、如果需要电动机连续运行，那么对于三相异步电动机功率的选择要注意什么？ 功率选择应该以产生机械所需要的实际功率为依据。选择的过大，效率和功率因数会很低，不经济。选择的过小，电动机长时间工作在外额定过载状态下，不仅

5、不能保证正常工作，还可能造成电动机损坏。4、基本放大电路的组成原则是什么？ 答： 1电路中既有直流通路，又有交流通路。2电路由线性元件和非线性器件组成。3三极管工作在放大状态，保证信号失真不超过允许范围。5、引入电压串联负反馈和电流并联负反馈，对放大电路的输入、输出电阻分别有什么影响？ 答：引入电压串联负反馈，会使输入电阻增大，输出电阻减小；引入电流并联负反馈，会使输入电阻减小，输出电阻增大。请您删除一下内容，O(_)O谢谢！2015年中央电大期末复习考试小抄大全，电大期末考试必备小抄，电大考试必过小抄After earning his spurs in the kitchens of The

6、 Westin, The Sheraton, Sens on the Bund, and a sprinkling of other top-notch venues, Simpson Lu fi nally got the chance to become his own boss in November 2010. Sort of. The Shanghai-born chef might not actually own California Pizza Kitchen (CPK) but he is in sole charge of both kitchen and frontof-

7、 house at this Sinan Mansionsstalwart. “Its certainly a responsibility to be the head chef, and then to have to manage the rest of the restaurant as well,“ the 31-year-old tells Enjoy Shanghai. “In hotels, for example, these jobs are strictly demarcated, so its a great opportunity to learn how a bus

8、iness operates across the board.“ It was a task that management back in sunny California evidently felt he was ready for, and a vote of confi dence from a company that, to date, has opened 250 outlets in 11 countries. And for added pressure, the Shanghai branch was also CPKs China debut. “For sure i

9、t was a big step, and unlike all their other Asia operations that are franchises, they decided to manage it directly to begin with,“ says Simpson. Two years ago a private franchisee took over the lease, but the links to CPK headquarters are still strong, with a mainland-based brand ambassador on han

10、d to ensure the business adheres to its ethos of creating “innovative, hearth-baked pizzas“, a slice of PR blurb that Simpson insists lives up to the hype. “They are very innovative,“ he says. “The problem with most fast food places is that they use the same sauce on every pizza and just change the

11、toppings. Every one of our 16 pizza sauces is a unique recipe that has been formulated to complement the toppings perfectly.“ The largely local customer base evidently agrees and on Saturday and Sunday, at least, the place is teeming. The kids-eat-for-free policy at weekends is undoubtedly a big dra

12、w, as well as is the spacious second-fl oor layout overlooked by a canopy of green from Fuxing Park over the road. The company is also focusing on increasing brand recognition and in recent years has taken part in outside events such as the regular California Week. Still, the sta are honest enough t

13、o admit that business could be better; as good, in fact, as in CPKs second outlet in the popular Kerry Parkside shopping mall in Pudong. “Sinan Mansions has really struggled to get the number of visitors that were envisaged when it first opened, and it hasnt been easy for any of the tenants here,“ a

14、dds Simpson. “Were planning a third outlet in the city in 2015, and we will probably choose a shopping mall again because of the better foot traffic.“ The tearooms once frequented by Coco Chanel and Marcel Proust are upping sticks and coming to Shanghai, Xu Junqian visits the Parisian outpost with s

15、weet treats. One thing the century-old Parisian tearoom Angelina has shown is that legendary fashion designer Coco Chanel not only had style and glamor but also boasted great taste in food, pastries in particular. One of the most popular tearooms in Paris, Angelina is famous for having once been fre

16、quented by celebrities such as Chanel and writer Marcel Proust. Now Angelina has packed up its French ambience, efficient service, and beautiful, comforting desserts and flown them to Shanghai. At the flagship dine-in and take-out space in Shanghai, everything mimics the original tearoom designed fr

17、om the beginning of the 20th century, in Paris, the height of “Belle Epoque“. The paintings on the wall, for example, are exactly the same as the one that depicts the landscape of southern France, the hometown of the owner; and the small tables are intentional imitations of the ones that Coco Chanel

18、 once sat at every afternoon for hot chocolate. The famous hot chocolate, known as LAfricain, is a luxurious mixture of four types of cocoa beans imported from Africa, blended in Paris and then shipped to Shanghai. Its sinfully sweet, rich and thick as if putting a bar of melting chocolate directly

19、on the tongue and the fresh whipped cream on the side makes a light, but equally gratifying contrast. It is also sold in glass bottles as takeaway. The signature Mont-Blanc chestnut cake consists of three parts: the pureed chestnut on top, the vanilla cream like stuffing, and the meringue as base. G

20、et all three layers in one scoop, not only for the different textures but also various flavors of sweetness. The dessert has maintained its popularity for a century, even in a country like France, perhaps the worlds most competitive place for desserts. A much overlooked pairing, is the Paris-New Yor

21、k choux pastry and N226 chocolate flavored tea. The choux pastry is a mouthful of airy pecan-flavored whipped cream, while the tea, a blend of black teas from China and Ceylon, cocoa and rose petals, offers a more subtle fragrance of flowers and chocolate. Ordering these two items, featuring a muted

22、 sweetness, makes it easier for you to fit into your little black dress. Breakfast, brunch, lunch and light supper are also served at the tearoom, “a hub of many cultures“ and takes in “a mix of different styles of French cuisines“, according to the management team. The semi-cooked foie gras terrine

23、, is seductive and deceptive. Its generously served at the size and shape of a toast, while the actual brioche toast is baked into a curved slice dipped with fig chutney. The flavor, however, is honest: strong, smooth and sublime. And you dont actually need the toast for crunchiness. This is the sea

24、son for high teas, with dainty cups of fine china and little pastries that appeal to both visual and physical appetites. But there is one high tea with a difference, and Pauline D. Loh finds out just exactly why it is special. Earl Grey tea and macarons are all very well for the crucial recuperative

25、 break in-between intensive bouts of holiday season shopping. And for those who prefer savory to sweet, there is still the selection of classic Chinese snacks called dim sum to satisfy and satiate. High tea is a meal to eat with eye and mouth, an in-between indulgence that should be light enough not

26、 to spoil dinner, but sufficiently robust to take the edge off the hunger that strikes hours after lunch. The afternoon tea special at Shang-Xi at the Four Seasons Hotel Pudong has just the right elements. It is a pampering meal, with touches of luxury that make the high tea session a treat in itsel

27、f. Whole baby abalones are braised and then topped on a shortcrust pastry shell, a sort of Chinese version of the Western vol-au-vent, but classier. Even classier is the dim sum staple shrimp dumpling or hargow, upgraded with the addition of slivers of midnight dark truffles. This is a master touch,

28、 and chef Simon Choi, who presides unchallenged at Shang-Xi, has scored a winner again. Sweet prawns and aromatic truffles whats not to love? His masterful craftsmanship is exhibited in yet another pastry a sweet pastry that is shaped to look like a walnut, but which you can put straight into the mo

29、uth. It crumbles immediately, and the slightly sweet, nutty morsel is so easy to eat youll probably reach straight for another. My favorite is the dessert that goes by the name yangzhi ganlu, or ambrosia from the gods. The hotel calls it chilled mango cream with sago, pomelo and birds nest made with

30、 ingredients that resonate with every female soul. It does taste like ambrosia, with the sweet-sour fragrance of the mango forming the first layer of taste and sensation, and the pomelo sacs and sago pearls providing the tactile contrast. The birds nest its the ingredient that gilds the lily, since it is supposed to nourish and n