電學計算功率

In AC Circuit,,

You May Use P=IV cos Theta,,

In Above Formula,,

P=Power(Watt)

I=Current(Ampere)

V=Voltage(Volt)

cos Theta Is The Power Factor,,

The Power Factor In Hong Kong Is 0.85

So The Max Power In AC Circuit Is,,

P = 13Ampere x 220Volt x 0.85

In DC Circuit,,

You May Just Use P=IV

In Above Formula,,

P=Power(Watt)

I=Current(Ampere)

V=Voltage(Volt)

If A Bulb Using AC220V,,

And The Current Is AC0.45A,,

The Power Factor Is 0.85,,

So

P = 0.45A x 220V x 0.85

P = 84.15(Watt)