题干

如图1所示电路,电源电压保持不变,当闭合开关S,调节滑动变阻器阻值从最大变化到最小,两个电阻的“U﹣I”关系图象如图2所示.则下列判断正确的是(   )

A:电源电压为10V

B:定值电阻R1的阻值为20Ω

C:滑动变阻器R2的阻值变化范围为0~10Ω

D:变阻器滑片在中点时,电流表示数为0.3A

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答案(点此获取答案解析)

D

同类题3

阅读下面材料, 在空白处填入适当内容 (一个单词)或括号内单词的适当形式。讲答案填写在答题纸的相应位置。
       What's the most important thing for you to have in your life? Somebody ____ (mention)hard-work, others suggest knowledge, love and luck.
       If you arrange the 26 English letters alphabetically(按字母表的顺序)and use ____(number)to represent each of them, for example, 1 for a, 2 for b, 3 for c…, you can change an English word into a number. So hard-work becomes 8+1+18+4+23+15+18+11=98, meaning 98 is its mark; knowledge: 11+14+15+23+12+5+4+7+5=96, while love :12+15+22+5=54, and luck : 12+21+3+11=47, a small mark. None of these words can give one a full mark. What about money or prayer(祈祷)? They can't , ____.
       Then what else? Don't be worried. You can always find an answer ____a problem in your life, ____you change your way of looking at things or doing things, or your attitude. Yes, attitude is the word. See for____(you): attitude:1+20+20+9+20+21+4+5=100, a full mark.
       Different attitudes lead to different courses of life. Most times people hope for a better life. It is possible ____one will have a change for the better after one has ____(change)one's attitude.
       When you change your manner and became friendly towards others, you'll meet ____ (much)smiling faces towards you. In the same way, if you take a positive attitude towards failure, you'll find it's also rewarding ____it has caused you losses.