题干

小林家新买了一台饮水机,小林的父母经常为夜间是否要关闭饮水机而发生争执:妈妈认为关机可以节省电能,理由是饮水机在夜间无人饮水时仍在对热水包里的水间歇性加热。爸爸则认为关机后第二天重新开机为凉水加热会消耗更多的电能。于是小林查到饮水机铭牌如下表所示,他决定用实验来化解父母的争执。
第一天晚上十点,他关掉家中的其他用电器,只保留饮水机的加热功能,记下此时电能表的示数为576.5 kW·h,第二天早晨六点钟,水温达到预定温度95℃,他又读出电能表的示数为576.8 kW·h。
第二天晚上十点,他将饮水机关闭,次日早晨启动,饮水机在额定功率下将水加热 到预定温度95℃,用时8min。
请解答下列问题:

⑴饮水机正常加热时的电流是多少?
⑵通过计算判断小明爸爸妈妈谁的方法更节能?

上一题 下一题 0.0难度 选择题 更新时间:2019-09-12 08:50:00

答案(点此获取答案解析)

解:⑴正常加热时:I=PU=880W220V=4A

同类题3

阅读下面短文,从短文后各题所给的A、B、C、D四个选项中,选出最佳选项。

    Gwondo was a trainer of dogs. He would go out every day with his dogs, to1 them how to catch animals so all his tribe(部落) could eat.

    Wherever Gwondo went, his tribe could see him away in the distance  2 his white hair would shine in the sunlight. The tribe 3would say to their children, "See, there is Gwondo and his dogs, searching for 4 for us all. " Gwondo went out hunting every day and always came 5 with much food. And all were very happy.

    Now Gwondo grew 6 and as all humans do, one day he died. The tribe felt sad and cried many days and many nights 7 one day the elders called to their children, " You have cried enough for Gwondo. Now it is time to 8 living. Go down to the beach and be happy."

    The children ran down to the beach and looked out to sea. 9, they all looked at each other, then turned and ran back to their elders, 10, "Come quickly. Gwondo, he is back with us. He is out in the sea. "The elders hurried to the 11 and said, "Yes! It is Gwondo back! He is now a dolphin and lives in the sea. "

    Now whenever you see 12 dolphins in the sea, look for the big old dolphin. You will know him because he has a large white fin on 13 back. He is Gwondo and he is training the young dolphins to chase(追逐) 14 close to the beach so that his tribe can catch them.

     Gwondo is known to all the tribes 15 the east coast of Australia. They call him their sea dog.