题干

电吹风是现代家庭的常见电器.如图是某简易电吹风工作原理的电路图(R为电热丝,M为电动机)该电吹风的铭牌见表.求:

 额定电压

 220V

 频率

 50Hz

 吹热风时功率

 1100W

 吹冷风时功率

100W

①电吹风正常工作且吹热风时,通过电热丝的电流.

②电热丝R的阻值(电热丝的阻值随温度变化忽略).

③电吹风正常工作且吹热风时,5min内电流通过R产生的热量.

④若电吹风工作时电热丝的实际功率为810W,此时供电的实际电压为多少?

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答案(点此获取答案解析)

解:①电热丝的发热功率为P=P﹣P=1100W﹣100W=1000W
通过电热丝的电流为I=
P
U
=

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阅读下面短文,从短文后各题所给的四个选项(A、B、C和D)中,选出可以填入空白处的最佳选项。

        People often say that you can not change the environment, but can change yourself; you can not change the past, but now can be changed; you can not change the facts, but can change attitudes.

        Indeed, one key to the success lies in his1. The difference between successful people and the losers are: 2 attribute setbacks and difficulties to personal ability, experience, imperfect, to  3 the internal(内在的), they are willing to continuously improve and develop the right direction; while the losers will blame on the opportunity, and the environment injustice, emphasizing external(外在的) and 4factors that created the position of their life, they always 5, wait and give up!

        Person's appearance or his family is a priori (先验的)condition that can not be changed, but at least the inner state, the spirit of the will is6in their control. Mentality determines the final height of life. There is no absolute bad thing, only the absolute7mentality. If a person even cannot8the state of mind, how can he deal with things more complicated than the mentality?

        No matter what the situation is, a person's9 is very important. That you put10 or numbness in your work makes completely different. Emerson said:When one keeps moving toward his goal,the whole world will stand away from his way.On the contrary, failure is not because we do not have the 11, but because we are susceptible(易受影响的) to all around us with an unstable attitude, and are easily 12.

        As long as we believe the power of mind, change our attitude and have the13to face the disappointments in life, do not despair, we can 14succeed. Believe the power of mind because15determines the final height of life.