问题 问答题 简答题

请简述光与物质的三种相互作用的意义。

答案

参考答案:

光与物质的三种相互作用形式分别为自发辐射、受激辐射、受激吸收。

自发辐射:在没有外界影响的条件下,处于原子高能级的电子会自发地向低能级跃迁而发光,这种发光过程称之为自发辐射;

受激辐射:在外界光子的激励下,处于原子中高能级的电子向低能级跃迁而发光,这种发光过程称之为受激辐射;

受激吸收:在外界光子的激励下,原子吸收外界激励的能量,使原子中的低能级电子跃迁到高能级,这种过程称之为受激吸收。

阅读理解

阅读理解。

     On the first day of my new high school, I almost had a nervous breakdown. Everything about the school

seemed so difficult. When I got home, my parents said, "You're nervous and that's okay. Everyone is afraid

of high school." I denied it. I wanted to be strong, so I refused to let anyone know about my fear, even my

closest friends.

     On the first day I was late for every class and was constantly lost. The school seemed like a puzzle that I

couldn't figure out. Was this how the whole year was going to be? I didn't think I could rise to this challenge,

especially carrying a huge backpack that I could hardly lift. It was so big that I could knock someone out with

it! The schoolmates seemed to regard me as a fool, and they were probably right.

     Despite my fears, after the first week I finally had my schedule figured out. With the exception of falling up

and down the stairs a couple of times and getting laughed at, high school was turning out to be not so bad. It

was actually much better than middle school and much more challenging.

     Since then, I've been elected vice president of my class, which wasn't much of a victory since only three

people ran for the four positions.

     It is normal to be scared about a new school. Take a deep breath and relax. High school is something that

any student can overcome. Make sure you participate in some out-of-class activities because you'll find it easier

to make friends. Try to do your best, even if it isn't straight A's.

     Most important of all, be who you are, whether you're a "fool", an athlete, or a lower grader. Don't try to

pretend to be someone you're not. Now you know the true secrets of high school.

1. The main reason for the author's fear on his first day is that _____.[ ]

A. he was unable to work out the puzzle

B. his schoolmates were unfriendly to him

C. he was not familiar with the new surroundings

D. his schoolbag was too heavy for him to carry

2. From the author's first day experience we can infer that _____. [ ]

A his home was far from the school 

B. he got to school after classes began

C. he didn't get any school schedule

D. he didn't know the right way to class

3. After his first week at school, the author _____. [ ]

A. was still not accustomed to the schedule

B. gradually adjusted himself to the new school

C. found high school not so challenging as he had imagined 

D. ran for president of his class against three other students

4. According to the passage, the secret of the author's success lies mainly in _____. [ ]

A. making more friends

B. getting more A's at school

C. being who he really is

D. joining in out-of-class activities

单项选择题