相关试题
【单选题】
确定正弦量的三要素为 ___。
A. 相位、初相位、相位差
B. 最大值、频率、初相角
C. 周期、频率、角频率
【单选题】
当电压为5V时,导体的电阻值为5欧,那么当电阻两端电压为2V时,电阻值为___欧。
【单选题】
对称负载接成星形时,三相总电流___。
A. 等于零
B. 等于其中一相电流的三倍
C. 等于其中一相电流。
【单选题】
一段有源支路如图1所示，AB两端的电压UAB为___。
A. 10 V
B. —2V
C. 2V
D. —10V
【单选题】
如图2电路中，等效电阻=___
A. 150Ω
B. 900Ω
C. 600Ω
D. 100Ω
【单选题】
电流表的读数是4A，则电路中电流表的读数是 ___
【单选题】
在R、L、C串联电路中，已知＝3Ω，＝5Ω，＝8Ω，则电路的性质为 ___。
A. 感性
B. 容性
C. 阻性
D. 不能确定
【单选题】
工业生产中大量的设备均为感性负载，功率因数往往很低，常采取___的方法来提高电网的功率因数。
A. 并联电容
B. 串联电容
C. 串联电感
D. 并联电感
【单选题】
交流电压表及电流表指示的数值是___
A. 平均值
B. 有效值
C. 最大值
D. 瞬时值
【单选题】
RLC串联电路发生谐振，，R=10Ω，Ω，则谐振时的感抗为___
A. 10Ω
B. 40Ω
C. 20Ω
D. 30Ω
【单选题】
RL从电路获得最大功率，此时RL=___。
【单选题】
使用电解电容时___。
A. 负极接高电位，正极接低电位
B. 正极接高电位，负极接低电位
C. 正极接高电位，负极也可以接高电位
D. 不分正负极
【单选题】
开关接1时，电压表的读数为___。
A. 0V
B. 0.2V
C. 1.96V
D. 2V
【单选题】
开关接2时，电流表的电流为___。
A. 0A
B. 10A
C. 0.2A
D. 约等于0.2A
【单选题】
开关接1时，电流表中流过的短路电流为___。
A. 0A
B. 0.2A
C. 10A
D. 约等于0.2A
【单选题】
正弦交流电常用的表达方法有___。
A. 解析式表示法
B. 波形图表示法
C. 相量表示法
D. 以上都是
【单选题】
电感两端的电压相位超前电流___。
A. 90°
B. 180°
C. 360°
D. 30°
【单选题】
电容两端的电压相位滞后电流___。
A. 30°
B. 90°
C. 180°
D. 360°
【单选题】
应用戴维南定理求含源二端网络的输入等效电阻是将网络内各电动势___
【单选题】
LC 选频振荡电路，当电路频率等于谐振频率时，电路性质为___。
A. 电阻性
B. 感性
C. 容性
D. 纯电容性
【单选题】
阻值为4Ω的电阻和容抗为3Ω的电容串联，总复数阻抗为___
A. 3+j4
B. 3-j4
C. 4+j3
D. 4-j3
【单选题】
电动势为10V，内阻为2Ω的电压源变换成电流源时，电流源的电流和内阻是___
A. 10A，2Ω
B. 20A，2Ω
C. 5A，2Ω
D. 2A，5Ω
【单选题】
电流为5A，内阻为2Ω的电流源变换成一个电压源时，电压源的电动势和内阻为___
A. 10V，2Ω
B. 2.5V，2Ω
C. 0.4V，2Ω
D. 4V，2Ω
【单选题】
额定电压都为220V的40W、60W、100W三灯泡串联在220V的电源中，它们的发热量由大到小排列为___
A. 100W 60W 40W
B. 40W 60W 100W
C. 100W 40W 60W
D. 60W 100W 40W
【单选题】
在正弦交流电的解析式i=ImSin(ωt +φ)中，φ表示___
A. 频率
B. 相位
C. 初相位
D. 相位差
【单选题】
正弦交流电压u=100Sin(628t + 600)V，它的最大值为___。
A. 100 V
B. 100 V
C. 60V
D. 628 V
【单选题】
能表示容性电路电压与电流关系的相量图是___。
【单选题】
电路中___定律指出：流入任意一节点的电流必定等于流出该节点的电流。
A. 欧姆
B. 基尔霍夫电流
C. 楞次
D. 基尔霍夫电压
【单选题】
已知电源电压为12 V ,四只相同灯泡的工作电压都是6 V，要使灯泡都能正常工作，则灯泡应___
A. 全部串联
B. 两只并联后与另两只串联
C. 两两串联后再并联
D. 全部并联
【单选题】
用戴维南定理分析电路“入端电阻”时，应将内部的电流源___处理。
【单选题】
任何一个含源二端网络都可以用一个适当的理想电压源与一电阻___来代替。
A. 串联
B. 并联
C. 串联或并联
D. 随意联接
【单选题】
用交流电流表测得交流电流10A，则电路中电流的最大值为___。
A. 10A
B. 14.1A
C. 20A
D. 70.7A
【单选题】
如右图所示电路中，已知各支路的电流I1=I2=10A， 则电路的总电流I为___。
A. 20A
B. 0 A
C. 14.1A
D. 50A
【单选题】
1杂质半导体中多数载流子的浓度取决于___
【单选题】
2在电场作用下，空穴与自由电子运动形成的电流方向___
【单选题】
4下列半导体材料哪一种的热敏性突出“导电性受温度影响最大”？___
A. 本征半导体
B. N型半导体质
C. P型半导体
推荐试题
【单选题】
It took me a long time to ___ the disappointment of failing the exam.
A. get over
B. get up
C. get into
D. get down
【单选题】
She ___ 100 pages of the book today.
A. has already read
B. already reads
C. already read
D. was already read
【单选题】
He has been ___ for nearly three weeks after the death of his dear pet.
A. sad
B. satisfied
C. evil
D. joyful
【单选题】
One cannot learn a foreign language well ___he studies hard.
A. unless
B. if
C. as
D. when
【单选题】
A large number of people___ present at the meeting, which was out of our expectation.
A. was
B. were
C. have
D. has
【单选题】
When the girls saw the funny man, they couldn't ___ laughing.
A. keep from
B. keep on
C. keep away
D. keep at
【单选题】
We are glad that we finally managed to get into contact ___ them.
A. at
B. on
C. from
D. with
【单选题】
This kind of plant___a lot of water at all times.
A. assumes
B. limits
C. produces
D. requires
【单选题】
Look! Here ___ the famous player.
A. comes
B. come
C. had come
D. coming
【单选题】
Uncle Sam sent him a___ bicycle as a birthday present.
A. red sports new
B. sports new red
C. new sports red
D. new red sports
【单选题】
I couldn't find my English-Chinese dictionary___.
A. anywhere
B. everywhere
C. nowhere
D. somewhere
【单选题】
The plane was about to___, and yet I left my ticket behind.
A. take off
B. take on
C. take up
D. take in
【单选题】
John succeeded ___ what he wanted.
A. to get
B. to getting
C. in getting
D. and getting
【单选题】
The accident was ___ to careless driving.
A. for
B. likely
C. due
D. because
【单选题】
With a good command of reading skills, most students can manage to read ___as they could the year before.
A. as twice fast
B. as fast as twice
C. as twice as fast
D. twice as fast
【单选题】
Some famous singers live on the ___from their record sales.
A. salary
B. price
C. bill
D. income
【单选题】
_____of them thinks that is a good idea.
A. Anyone
B. No one
C. None
D. Someone
【单选题】
Don't be too ___about things you're not supposed to know.
A. strange
B. amusing
C. curious
D. conscious
【单选题】
It was in 1969 ___the American astronauts succeeded in landing on the moon.
A. when
B. the moment
C. which
D. that
【单选题】
___people in the world are sending information by e-mail every day.
A. Several million
B. Many millions
C. Several millions
D. Many million
【单选题】
He___less time reading stories about film stars than before.
A. takes
B. spends
C. costs
D. pays
【单选题】
Selecting a mobile phone for personal use is no easy task because technology___so rapidly.
A. is changing
B. has been changed
C. will have changed
D. will change
【单选题】
The taxi driver always reminds passengers to ___their belongings when they leave the car.
A. keep
B. catch
C. hold
D. take
【单选题】
Little Tom is used to getting up ___eight every morning.
【单选题】
If the doctor had been available, the child _______.
A. would not die
B. could not have died
C. might not die
D. should not have died
【单选题】
If Mary___shopping this afternoon, please ask her to write a shopping list first.
A. will go
B. goes
C. went
D. has gone
【单选题】
These desks and chairs ___to the children in the mountain villages next week.
A. are sent
B. will send
C. have sent
D. will be sent
【单选题】
Every society has its own peculiar customs and ___of acting.
A. attitudes
B. behavior
C. ways
D. means
【单选题】
China is ___the Great Wall.
A. on
B. famous
C. famous for
D. famous as
【单选题】
The dog was tearing the cloth___its teeth.
A. with
B. by
C. through
D. in
【单选题】
A man should not be judged always ___what he says.
A. by
B. in
C. with
D. to
【单选题】
We will have a ___holiday after the exam.
A. two month
B. two-month
C. two month's
D. two-months
【单选题】
Mr Wang is going to teach you maths ___one year.
A. with
B. on
C. for
D. to
【单选题】
The population of the earth ___increasing fast.
A. is
B. are
C. were
D. have been
【单选题】
Mike is ___than Jack.
A. careful
B. carefully
C. less careful
D. more carefuler
【单选题】
There ___a basket ball match this afternoon.
A. is going to be
B. is going to have
C. is going to is
D. is going to has
【单选题】
Nobody ____to smoke in the cinema.
A. allow
B. allows
C. is allowed
D. are allowed
【单选题】
___delicious these moon cake are!
A. How a
B. What a
C. How
D. What
【单选题】
There's no food in the fridge. They ___shopping.
A. go
B. are go
C. are going
D. are going to go
【单选题】
The soup smells___. Would you like some?
A. good
B. well
C. properly
D. finely
