问题 选择题

以下说法正确的是(  )

A.电场中某点电场强度的方向,就是置于该点的正检验电荷所受电场力的方向

B.由E=

F
q
可知此场中某点的电场强度E与F成正比

C.由公式∅=

EP
q
可知电场中某点的电势φ与q成反比

D.由Uab=Ed可知,匀强电场中的任意两点a、b间的距离越大,两点间的电势差也一定越大

答案

解;A、某点的电场强度的方向就是处于该点的正电荷所受电场力的方向,与负电荷所受电场力的方向相反,故A正确.

B、电场强度是由电场本身决定,与试探电荷的有无,电性,所受电场力的大小、方向都无关,故B错误.

C、电势φ的大小与电场本身有关,与零电势的选取有关,而与与试探电荷的有无,电性无关,故C错误.

D、电场中两点的电势差,由电场本身决定,根据U=Ed可得在沿电场线方向上ab两点的距离越大,在场强不变的情况下,两点之间的电势差越大,故所谓两点不能是任意两点,只能是沿电场线方向的两点,故D错误.

故选A.

阅读理解

阅读理解。

       Michelle Kwan is a famous American figure skater  ( 花样滑冰运动员 ).  Many young people like

her a lot.  She is half-Chinese and was born on July 7,  1980.  Her hometown is in Guangdong, China.  

Her mother is an American.  Michelle is the youngest of their three children.  She has a brother and a

sister.  They also like figure skating.

      Michelle has won seven National Championships of America and has won eight medals at the World Championships.  She has also won two Olympic medals.  She got the third place in 1998, and the second

in 2002.  When she talks about her success, she says, "My parents taught mc to work hard. If you do,

your dreams may come true."

      She also says,  "What you give is what you get back. " In the future,  the popular skate: wants to be

the Michael Jordan of her sport.

1.There are______people in Kwan's family.

A. 3

B. 4

C. 5

D. 6

2. She's a half-Chinese because______.

A.her mum is Chinese and her dad is American

B.her dad is Chinese and her mum is American

C.both of her parents are Chinese except her

D.she has a brother and a sister

3. In the 2002 Olympic Games Michelle Kwan got______in the 1998 Olympic Games.

A.a worse medal than

B.a better medal than

C.a medal as good as

D.We don't know.

4. The secret of Kwan's success is______.

A.to work hard

B.to give less

C. to get more

D. to smile to others

5. The last sentence in the passage means Kwan wants to______.

A.play basketball instead of skating

B.learn basketball from Jordan

C. be the best figure skater

D.practice basketball and skating

问答题 简答题