问题 问答题

一束单色光在真空中波长为6.00×10-7 m,该单色光的频率为______Hz(真空中光速是3.00×108 m/s).该单色光射入折射率为1.50的玻璃中,它在此玻璃中的波长为______m.

答案

由c=λf得:

 f=

c
λ
=
3×108
6×10-7
Hz=5.00×1014Hz

设它在此玻璃中的波长为λ′,因为该单色光进入玻璃中时频率不变,则有

  n=

c
v
=
λf
λ′f
=
λ
λ′

则得:λ′=

λ
n
=
6×10-7
1.5
m=4.00×10-7m

故答案为:5.00×1014,4.00×10-7

选择题
阅读理解

     Started in 1636, Harvard University is the oldest of all the colleges and universities in the United 

States. Yale, Princeton, and Columbia were opened soon after Harvard. In the early years, these 

schools were much alike. Only young men could go to college. All the students studied the same 

subjects, and everyone learned Latin, and Greek. Little was known about science then. When the 

students graduated, most of them became ministers or teachers.

     In 1782, Harvard started a medical school for young men who wanted to become doctors. Later, 

lawyers could receive their training (训练) in Harvard's law school. In 1825, besides Latin and 

Greek, Harvard began teaching modern languages, such as French and German. Soon it began teaching 

American history.

     As knowledge increased, Harvard and other colleges began to teach many new subjects. Students 

were allowed to choose the subjects that interested them. Today, there are many different kinds of 

colleges and universities. Most of them are made up of smaller schools that deal with special fields of

learning. There's so much to learn that one kind of school can't offer it all.

1. The oldest university in the US is ______.

A. Yale

B. Harvard      

C. Princeton

D. Columbia

2. Which of the following statements is TRUE?

A. Those colleges and universities were the same.

B. People, young or old, might study in the colleges.

C. Students studied only some languages and science.

D. When the students finished their school, they all became lawyers or teachers.

3. As knowledge increased, colleges began to teach ______.

A. everything that was known

B. law and something about medicine

C. many new subjects

D. the subjects that interested students

4. On the whole, the passage is about ______.

A. how to start a university

B. the world-famous colleges in America

C. how colleges have changed

D. what kinds of lessons each college teaches