问答题

【计算题】一只电流表满量限为10A，准确等级为0.5,用此表测量1A电流时的相对误差是多少?

答案：

最大相对误差△m=0.5%×10=±0.05(A),测量1A的电流时,其相对误差为±0.05/1×100%=±5%。

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单项选择题

SECTION A CONVERSATIONS
Directions: In this section you will hear several conversations. Listen to the conversations carefully and then answer the questions that follow.
听力原文：Sally: Now, specifically in that sen6, you mention 'Lisa'. Is there actually a 'Lisa' out there?
Elliot: Yes, there really is. She was somebody I went out with for two years actually.
Sally: What happened later?
Elliot: Her dad Just didn't want it to happen so bad that she just couldn't take the pressure.
Sally: You must have felt bitter about the whole split up and everything?
Elliot: It’s really tough, she wants to do something with her life and her dad’s threatening to out off her college tuition if she continues to see me, so it's like she had a serious decision to make.
Sally: Were you hitter about her?
Elliot: Like I said, at first, I was somewhat bitter but I understand, I guess. I don't know. I know I probably wouldn't have done the same thins. Who knows, people are different, so I couldn’t really hold that against her.
Sally: What has she said to you since she heard it on the radio?
Elliot: Oh, I haven’t heard from her.
Sally: You haven’t?
Elliot: I dropped some notes for her to call me some time but she hasn’t, I guess at this point, I don’t expect her to. That' e my call out to her, because I have no idea.
Who is true of Lisa?
A．Lisa is the man who is speaking to the man.
B．Lisa is the girl whom the man dated two years ago.
C．Lisa is the girl whom the man dated for two years.
D．Lisa is a woman whose name appears in one of the man’s song.

A.
听力原文：Sally:
B.
Sally:
C.
Sally:
D.
Sally:
E.
Sally:
F.
Sally:
G.
Who
H.Lisa
I.
B．Lisa
J.
C．Lisa
K.
D．Lisa
L.

【简答题】有一全阻抗继电器整定阻抗为5Ω/ph，当测量阻抗为（4+4j）Ω/ph时，继电器能否动作？

答案：

当测量阻抗为(4+4j)Ω/ph，其模值为5.66Ω,大于整定值阻抗,故继电器不动作。