一只标有“220V 1000W”的电炉正常工作时的电阻是______Ω，电流是______A．
（1）“220V 1000W”表示电炉的额定电压U额=220V，电炉的额定功率P额=1000W；
（2）电炉正常工作时，其两端的电压为额定电压，发挥的功率为额定功率：
①电炉的电阻为R=
=U额2 P额
=48.4Ω；(220V)2 1000W
②电路的电流为I=
=P额 U额
=4.5A．1000W 220V
故答案为：48.4、4.5．
| 根据情景选择句子补全对话。 | |
| A: how long have you been learning English, Wang Hai? B: For six years. 1 . A: Really? 2 B: I can't get the pronunciation right. A: Well, listening can help. 3 ? You can listen to them at home and repeat the sentences that are difficult for you. B: That's a good idea. 4 ? I forget a lot of new words. A: You can always write the new words in your notebook and study them at home. You can even study in the train on the way to school. B: That might really help! The only other problem I have is that I don't get much writing practice. A: 5 . B: That sounds like a fun way to practice writing. Thanks, Mr. White. | |
|