现有几只电热管不知道是多少KW的,经过万用表测量后已知道电阻.如何知道是多少kw的?现有几只电热管不知道是多少KW的,经过万用表测量后已知道电阻.如何知道是多少kw的电热管?另外如何知道要使用多少平方的电线?既：已知电阻求功率?如何换算?补充：假设我知道现在一根电热管电阻是34.5（欧姆）如何算出是多少kw的电热管？

单项交流电功率计算公式：P=UIcosφ=I²R 。电线选择，是根据电流大小查表即可知道采用多大的截面的电线了。
知道了电阻，再测一下电流就可以按上式计算功率了。

电加热器都是正温度系数材料做的，只有达到额定功率时，测量的电阻才是电加热管的真实温度，在冷态时测量的数值来推断电加热器的功率是不准的。单相电加热管的电流是每千瓦4.5A，三相电加热每相电流为1.8A。

* Select a local ,Stylish and health MBT shoes swept the globe in tr,ken griffey jr shoesstore namely caters shoes as walkers and spend time with folk to appropriate right
* After the usual wading distance give your feet a become for they swell while walking
* Carry the usual socks you dress for walking before the selection of the shoe
* Take along with you the present walking shoe you are using so that the vendor can see the pattern of wear
* Share with the stores the usual distance,MBT boot bargain in a cheap cost, speed and frequency of your walking
* Select walking shoes half size larger than the clothes shoes
* The shoe you elect should be malleable and when you bend the toe towards heel the shoe should flex by the pellet of the foot
* Place the boot on a smooth surface and when you press the toe down look that the heel rises off the surface
* The heel ought not be many higher than the sole and it should not be flared
* Try the shoe with your regular walking pace. Check for the heel retention and scrutinize for over-pronation or other problems
* You must replace the shoes every 500 miles
When the shoes are flexible you will be capable to bend and distort the shoes. When you come from with your walking,Stylish and health MBT shoes swept the world in trend of discount MBT shoes , your tread will flex as you coil through a tread from heel to toe. In other words if the shoe is too stiff, your foot will fight it with every step you make.
Nowadays many contest walkers in Europe wear boots for long walking it may be inflexible and cumbersome.
Most of the walkers buffet with the heel 1st, so it is better to use a slightly undercut heel, that will be agreeable for walking.
The staff ambition make you walk and watch your manner of walk alternatively they ambition make you walk on a treadmill with assorted types of shoes before suggesting you the one which is best for you.
Make sure that you provide in the right shoes to lest harm and keep you walking with solace and ease. Never spend too much money on stylish shoes that will not fulfil well with your walking.
Tips for selection:
The general intention sporting merchandise stores do not keep staffs for the shoe department who are specialists on shoe fitting. To avail a better service, it is always best to work to a special running and walking shoe store in your zone.
It is favored that the walking shoes should have a flat heel.

U/R=I,I*U（相电压）*0.8（系数）=W！应该是吧！

电热丝具有温度效应,随着温度的升高,电阻会变大.电热管在正常工作时的电阻,要比冷态时大得多.用万用表测量的就是电热管的冷态电阻,用这个电阻值算不出电热管的发热功率.要知道它的功率,只能加上额定电压,测量流过的电流再用公式I*U得到.再有就是用比较法：先测得一些常用的已知功率大小的电热管的冷态电阻值,然后测量未知电热管的电阻和其比较,得出功率的大小.知道了功率,用P/U,算出电流大小,查电工手册,就知道该用多大的导线.