问题 填空题

光从水中斜射入空气,入射角减小,则折射角______,但折射角始终______入射角.如图是光从空气斜射入水中,入射光线是______,反射光线是______,折射光线是______,法线是______.

答案

(1)在光的折射现象中,当光从水中斜射入空气,入射角减小,则折射角随着减小,但折射角始终大于入射角;

(2)仔细分析题图,先分析哪是界面,OA、BO、OC不可能是界面,只有EF和GH是界面.

假设界面是GH,那么EF就是法线,利用光的反射定律,入射光线、反射光线必在同一种介质内,

并且折射光线和入射光线分居在法线的两侧,OC应是入射光线,OA是反射光线,BO是折射光线,

反射角(∠COE)和入射角(∠AOE)不相等,不符合光的反射定律.假设不成立.

因此只有EF是界面,GH是法线.

然后即可知,BO是入射光线,OA是反射光线,OC是折射光线.

故答案为:减小;大于;BO;OA;OC;GH.

多项选择题
阅读理解

阅读理解。

     Brave Frenchman Found Half-way Around the World (NEW YORK)

     A French tourist highly praised for rescuing a two-year-old girl in Manhattan said he didn't think twice

before diving into the freezing East River.

     Tuesday's Daily News said 29-year-old Julien Duret from France is the man who left the spot quickly

after the rescue last Saturday. 

     He lifted the little girl out of the water after she fell off the bank at the South Street Seaport museum.

He handed the girl to her father, David Anderson, who had dived in after him.

     "I didn't think at all," Duret told the Daily News. "It happened very fast. I reacted very fast."

     Duret, an engineer on vacation, was walking with his girlfriend along the pier (码头) when he saw

something falling into the water. He thought it was a doll, but realized it was a child when he approached

the river. In an instant, he took off his coat and jumped into the water.

     When he reached the girl, she appeared lifeless, he said. Fortunately, when she was out of the water,

she opened her eyes.

     Anderson said his daughter slipped off the bank when he was adjusting his camera. An ambulance came

later for her, said Duret, who was handed dry clothes from onlookers. Duret caught a taxi with his girlfriend

shortly after.

     The rescue happened on the day before he left for France. Duret said he didn't realize his tale of heroism

had greatly moved New York until he was leaving the city the next morning.

     "I don't really think I'm a hero," said Duret. "Anyone would do the same thing."

1. Why was Duret in New York? [ ]

A. To meet his girlfriend.

B. To work as an engineer.

C. To spend his holiday.

D. To visit the Andersons.

2. What did Duret do shortly after the ambulance came?[ ]

A. He was interviewed by a newspaper.

B. He asked his girlfriend for his dry clothes.

C. He went to the hospital in the ambulance.

D. He disappeared from the spot quickly.

3. When was Duret most probably found to be the very hero? [ ]

A. The day when he was leaving for home.

B. A couple of days after the girl was rescued.

C. The first day when he was in New York.

D. The same day when he was interviewed.