问题 问答题

如图所示,下部是在实验室观察光的干涉、衍射的实验装置,上部是通过该装置获得的红光双缝干涉和单缝衍射图样,可以看出,干涉图样与衍射图样之间有许多共同点、和不同点,请通过比较各写出其中的一点:

相同点:______;

不同点:______.

答案

两种条纹的相同点是:都是明暗相间的条纹.不同点:衍射的中央条纹特别宽、特别亮,而干涉条纹宽度相等、亮度相等.故答案为:都有明暗相间的条纹

衍射的中央条纹特别宽、特别亮,而干涉条纹宽度相等、亮度相等.

单项选择题
单项选择题

George Williams, one of Scottsdale’s last remaining cowboys, has been raising horses and cattle on his 120 acres for 20 years. The cattle go to the slaughterhouse, the horses to rodeos. But Mr. Williams is stomping mad. His problems began last year when dishonest neighbours started to steal his cattle. Then other neighbours, most of them newcomers, took offence at his horses roaming on their properties.

Such grumbles are common in Arizona. The most recent Department of Agriculture census shows that 1 213 of Arizona’s 8 507 farms closed down between 1997 and 2002. Many cattlemen are moving out to remoter parts of the state.

Doc Lane is an executive at the Arizona Cattlemen’s Association, a trade group. He says Arizona’s larger ranch owners are making decent profits from selling. It is the smaller players who are the victims of rising land values, higher mortgages and stiffer city council rules. What happens all too often is that people move in next to a farm because they think the land pretty. But soon they start complaining to the council. In Mr. Williams’s case it was the horses that annoyed them. Other newcomers don’t like the noise, the pesticides and the smell of manure.

Locals worry about the precious, dwindling cowboy culture. Arizona’s tourism boards like to promote a steady interest in all things about cowboy and western. Last year more British and German tourists came than usual, and many of them were looking precisely for that. Arizona’s Dude Ranch Association fills its $ 350-a-night luxury ranches most of the year; roughly a third of the guests are European.

Many of the ranchers themselves see all this tourism as a cheeky attempt to commercialise a real and vanishing culture. In Prescott, estate agents promote "American Ranch-style" homes with posters of horse riders. On the other side of the street is Whiskey Row, a famous strip of historic cowboy bars. But in Matt’s Saloon on Saturday night, real cattlemen could not be found.

Farm folk like Mr. Knox and Mr. Williams are weighing up their options. Many will migrate to remoter places where land is cheaper and not crowded with city people. Younger ones take on side-jobs as contractors and are cattle-hands part-time. Older cowboys aren’t sure what to do.

The pesticides and the smell of manure are mentioned to ()

A. explain why newcomers complain to the council

B. introduce the place in which cowboys live

C. explain why smaller players become victims

D. explain why cattlemen are moving out to remoter parts of the state