There are three 470ohm resistors are connected in series with a 48V source.What is the minimum power rating of the resistors?正确答案是0.543W,谁能解释一下为何3个同样的电阻还有最小值可言?如何计算出这个结果的,

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There are three 470ohm resistors are connected in series with a 48V source.What is the minimum power rating of the resistors?正确答案是0.543W,谁能解释一下为何3个同样的电阻还有最小值可言?如何计算出这个结果的,
There are three 470ohm resistors are connected in series with a 48V source.What is the minimum power rating of the resistors?正确答案是0.543W,谁能解释一下为何3个同样的电阻还有最小值可言?如何计算出这个结果的,

There are three 470ohm resistors are connected in series with a 48V source.What is the minimum power rating of the resistors?正确答案是0.543W,谁能解释一下为何3个同样的电阻还有最小值可言?如何计算出这个结果的,
晕,你对电阻的参数有一个误解.
电阻的参数除了阻值外,还有一个参数,表征它能够通过的最大电流.通常是用功率表示的,中文叫做额定功率,英文叫做power rating.
这道题是问你这三个电阻的额定功率最小可以是多少（再小就会被烧掉）.
I=48/(3*470)
P=IIR,这个就是每个电阻的实际耗散功率,power rating必须大于这个功率,否则电阻就会烧.

不是最小值。
是单独一个电阻的功率。
P=U^2/r
即48*48/（3*470）≈0.543

3个470ohm电阻串联在48V的电路里。电阻的最低额定功率是多大？
算出3个电阻在电路中的实际功率，电阻的额定功率不能小于电阻在电路中的实际功率，那么电阻的最低额定功率就是电阻在电路中的实际功率。
电阻在电路中的电流：I=U/R=48/(470*3)
电阻在电路中的实际功率：P=UI=48*48/(470*3)
每个电阻的实际功率：P/3=48*48/(470*3...

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3个470ohm电阻串联在48V的电路里。电阻的最低额定功率是多大？
算出3个电阻在电路中的实际功率，电阻的额定功率不能小于电阻在电路中的实际功率，那么电阻的最低额定功率就是电阻在电路中的实际功率。
电阻在电路中的电流：I=U/R=48/(470*3)
电阻在电路中的实际功率：P=UI=48*48/(470*3)
每个电阻的实际功率：P/3=48*48/(470*3*3)=0.545W
注意如果是电阻实际选型，在电阻规格里没有0.545W这个规格的产品，在电阻的规格里只有0.25W、0.5W、1W、2W等规格，“额定功率不小于实际功率”，那么应选用1W的。

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