题目

教室里日光灯两端的电压为______伏，日光灯与投影仪是____ 连接的（选填“串联”或“并联”），关闭几盏灯后电路中的总电阻将 ____ （选填“变大”、“变小”或“不变”）。额定功率为0.04千瓦的日光灯正常工作5小时，耗电_____度，消耗的电能用____表测量。 答案：【答案】 220 并联 变大 0.2 电能【解析】家庭电路电压为220V，家用电器通常是并联在电路中的。所以教室里日光灯两端的电压为220伏，日光灯与投影仪是并联；根据电阻并联的特点，电阻并联相当于增加了导体的横截面积，所以电阻变小，即并联电阻个数越多电阻越小，并联电阻个数越少，电阻越大。A Using a,an and theA1.Complete the questions and answers with a,an or the. Put a cross (×) in the blanks if no articles are needed.1 Q: Is there library near here?A: Yes. Beijing Library is just on corner of this street.2 Q: Do you have dictionary? I need English dictionary.A: Yes. There's dictionary on my desk.3 Q: Is there post office near your home?A: Yes,there is. It's at the end of road.4 Q: Is New York capital of USA?A: No. Washington   D. C. is capital.5 Q: Are you going to play basketball after school?A: No. I'm going to cinema with Peter.