题目

如图所示，电阻 R 与小灯泡 L 连接在电路中，当闭合开关 S1、S2 时，灯泡的电功率为 9W；S1 闭合 S2 断开时，灯泡的电功率为 1W（不考虑灯泡的电阻随温度而发生变化），则此时电阻 R 消耗的电功率为_____W，1min 内电路消耗的电能为_____J。 答案：【答案】2180【解析】由电路图可知,当闭合开关S1、S2时，电阻R被短路，只有灯泡接入电路，灯泡两端电压等于电源电压，由P＝得：RL＝；由电路图可知,当S1闭合、S2断开时，灯泡L与电阻R串联，根据P＝得：RL＝，所以：，则：，由此可得：U:UL＝3:1，串联电路的电压等于各分电压之和,所以UR:UL＝2:1，串联阅读表达Almost every child in cities has the chance to go to school, but not all children in the countryside are so lucky.There is a girl called Xiao Juan. She is ten years old and lives in a small village. When she was seven, she wanted to go to school. But she could not, because her family was too poor to afford the 2school fees for her, so her parents had to keep her at home. Instead of studying, Xiao Juan looked after her brother and worked in the fields every day. Then Hope Project heard about Xiao Juan. It agreed to help Xiao Juan to go to school. Her wish of study came true, and now she is studying in a school.Unluckily, there are many thousands of children who can not go to school. You can join in Hope Project and help these children. You know all the good work needs money. Hope Project needs your help.If you give Hope Project ￥300 each year, it can pay for one child to go school for a whole year. With more money, Hope Project can build new schools; buy good desks, chairs, blackboards and books. Let’s help the children together and give them a chance to have a good start in life.Information Card1.Where does Xiao Juan live?______________________.2.What’s the Chinese meaning of “school fees”?____________3.What did Xiao Juan do before she goes to school?______________________________________.4.把划线句子翻译成汉语。________________________________________.5.What is the purpose of Hope Project?________________________________________.