有一只小灯泡，正常发光电阻为6欧正常工作电压3V将塔接到8V电压

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问题填空题

有一只小灯泡，正常发光电阻为6欧正常工作电压3V将塔接到8V电压上，使其正常发光需要串联______Ω电阻．

答案

因为电路两端电压大于灯泡的额定电压，因此需要串联一个电阻分压；

又因为灯泡正常发光，因此电路中的电流为 I=

6Ω

=0.5A；

串联电阻两端的电压为 U′=8V-3V=5V，I′=I

串联电阻为 R′=

U′

I′

0.5A

=10Ω．

故答案为 10．

阅读理解

阅读下面短文，然后根据短文内容回答问题。

Amanda has a big room. A desk is on the floor.A comfortable chair is near the desk. Many books

and a computer are on the desk. Next to the desk is a dresser.An alarm clock is on the dresser. The

alarm clock wakes her up every day. The wall is pink. That's her favorite color. On the wall, we can see

her family photo. Look, she also has a pink bed.Now her cat is sleeping on the bed.Do you like her

room?

1.Where's the chair?

_______________________________________________________________________

2.Where's the alarm clock?

_______________________________________________________________________

3.Where's her family photo?

_______________________________________________________________________

4.Where's her cat?

_______________________________________________________________________

5.What color is the Wall?

_______________________________________________________________________

选择题

2013年央视“3·15晚会”曝光：江淮汽车为获取更大利润，占有更大汽车销售市场，没有使用合格的镀锌板，而使用便宜的普通钢板，造成车身鼓包、腐烂，安全性能下降。该企业行为

①侵犯了消费者的合法权益 ②违背了诚实守信原则

③有利于企业的长远发展 ④是一种不正当竞争行为

A．①②③

B．②③④

C．①③④

D．①②④