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Electric Cars: Low-impact Vehicle After years of false starts, General Motors has at last set a date for putting its first battery-powered car into production. The EV1 that will roll out of GM's factory in Lansing, Michigan, later this year will be the first car in modern times to have been specifically designed by a big car maker to run on electricity. A proper marketing of electric cars? The timing is intriguing. GM has announced its decision just as California's regulators are preparing to relax the strict air quality standards that were an important reason for going ahead with the project in the first place. The California Air Resources Board decided in 1990 that 2% of the vehicles sold in that state by the seven companies with the largest market share would have to be emission-free — in other words — electric-starting in 1998. By 2003, the board wanted the figure to be 10%. Now it admits that 'new studies' have shown what everyone else knew all along: that its mandate (命令)would be impossible to meet using existing battery technology. Many challenges faced This is because without official bullying, people are reluctant to buy electric cars. Although the EV1 has been loaded with all sorts of baubles(花哨的小玩意儿) — dual air bags, air conditioning, power windows, even a CD stereo system — it is far from clear that these will compensate for a puny range, the basic flaw of every electrical vehicle. Publicly, GM officials claim that the car will have to be recharged every 145 km (90 miles) or so, but they concede privately that the real figure is likely to be close to 100 km. Without access to a high-speed charger, such a refill will take around 15 hours. Even squeezing this much range out of the EV1 has required a lot of engineering sleight (灵巧)of hand. Around 400 kg (900 lb) of lead-acid batteries are secreted about its body. To help compensate for all this weight, and to maximize the distance it can cover, the vehicle is equipped with low-rolling- resistance tyres, an aluminum chassis (底盘), a wind-cheating plastic skin and a regenerative braking system that helps to recapture energy normally lost when the brakes are applied. Even the tear-drop body shape should cut down wind resistance. Owners of an EV1 will have two ways of charging it. Those without access to a g20-volt power supply (most American domestic circuits are 110 volts) will have to do it the hard, 15-hour, way by plugging into a normal socket in the boot. But the preferred method is more ingenious(巧妙的): use of a paddle-like contraption (发明) that is inserted into a small slot in the car's nose. This operates by induction(电磁感应), eliminating the risk of sparks that might ignite the hydrogen released during recharging. At 220 volts the paddle can give an EV1 the electrical equivalent of a full tank in three hours. Super-charged versions of the device, designed for use in service stations, shopping-malls and fast-food restaurants, can bring the batteries up to 80% strength in mere 15 minutes. The fate of the EV1 could therefore be determined by GM's success in convincing the owners of such establishments to install these special chargers, thus creating a convenient alternative to petrol pumps for keeping a car fuelled up. The EV1 will be sold at a price of $ 35,000 through GM's Saturn dealerships and, in an unusual move, under the GM brand — the first time a product has been sold using the corporation's own name. It will initially be available only in four cities in southern California and Arizona. Environmental regulators in several other smog-bound states are also hoping to develop a market for electric vehicles, but GM's engineers feel that the EV1's lead-acid batteries would not function well in the sort of frigid conditions now blanketing the north-eastern states. Cold weather reduces a battery's power and life, and increases tyre fri

A.
Y
B.
N
C.
NG
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【单选题】关于电磁感应,下列叙述正确的是( )

A.
通电导体在磁场中受力,这种现象叫做电磁感应
B.
闭合电路在磁场中做切割磁感线运动,电路中一定会产生电流
C.
电磁感应现象说明利用磁场可以产生电流
D.
电磁感应现象中,电能转化成机械能

【多选题】[ 多选 ] 如图所示是电磁炉的工作原理示意图,电磁炉的内部有一个金属线圈,当变化的电流通过线圈时,会产生变化的磁场,使铁质锅底产生电磁感应现象,锅底发热,从而起到加热物体的作用。这种加热方式能减少热量传递的中间环节,可大大提升制热效率。以下关于电磁炉工作原理的说法中正确的是 ( )

A.
变化的电流通过线圈,会产生变化的磁场,这属于电流的磁效应
B.
电磁炉是利用变化的磁场产生涡流,铁质锅底迅速升温,进而对锅内食物加热的
C.
电磁炉是利用变化的磁场在食物中产生涡流对食物加热的
D.
电磁炉工作过程中是将电能直接转化为食物的内能

【单选题】下列现象中,属于电磁感应现象的是( )

A.
变化的磁场使闭合电路产生感应电流
B.
磁场对电流产生力的作用
C.
插入通电螺线管中的软铁棒被磁化
D.
电流周围产生磁场