问题 选择题

如图所示,真空中的平行板电容器带有一定的电荷量Q,静电计的指针偏角为θ.若减小两极板的正对面积S,同时增大两极板间的距离d,关于极板间的电势差U及指针的偏角变化情况,下列说法中正确的是(  )

A.U变小,θ变大

B.U变小,θ变小

C.U变大,θ变大

D.U变大,θ变小

答案

由C=ɛ

s
4πkd
可知,电容与正对面积成正比,与两板间的距离成反比;故减小正对面积、增大两极板间的距离时,电容器的电容减小;则由C=
Q
U
可知,两板间的电势差变大;而指针偏角显示的是电势差的变化,故可知指角偏角变大;

故选:C.

阅读理解

I remember the first time that I was extremely happy, I was about 8 years old when for the first time, there was a computer in the classroom. I remember that my teacher allowed each student to take turns to play various educational games on the computer. One day, I found the source code for one of these games. Without knowing or being taught any programming language, I was able to figure out some of the BASIC code. I just gave myself a limitless number of lives in the game, so I could continue playing it forever. This was also my first introduction to algebra, and I didn’t even know it at the time. This was a decisive moment in my life. I was quite excited because of what I was learning and what I was able to do. As a result, I was enthusiastic for the rest of my life about self-learning and computers, and I was quite happy doing them too.

I’ve noticed that people who are truly content with life are enthusiastic about what they do. This enthusiasm, along with good health, is the key to being happy. It also leads to self-confidence and content in life too. It may also lead to success, wealth and achievements.

Success, wealth or achievements can also bring some people happiness, yet I know plenty of rich people who are unhappy. I know many people with successful businesses that are not happy with what they are doing. I know people who continuously buy themselves new toys, such as cars, computers, and televisions, yet never seem content for too long. Please remember, happiness is the journey of life, not the destination.

小题1:What can we know from Paragraph 1?

A.The author has a great talent for algebra.

B.Creative thinking is necessary for every child.

C.The BASIC code of the computer is not difficult.

D.The author’s experience in his childhood changed his life.小题2:The author wants to tell us through the first paragraph that____.

A.interest is the best teacher

B.children are the hope of the future

C.young people are fearless

D.where there’s a will , there’s a way小题3:What is the secret of happiness in the author’s opinion?

A.Success and wealth.

B.Gifts and self-confidence.

C.Enthusiasm and good health.

D.Knowledge and achievements.小题4:We can infer from the last paragraph that ______.

A.rich people generally feel unhappy

B.wealth can’t bring people any happiness

C.one will feel unhappy once he has gained all the things he wants

D.being enthusiastic about what you are doing is more important than wealth

多项选择题