Power Factor

[73polarbear]

If a coil with a .2 lagging power factor is connected in series with 300 watt incandescent lamp to supply that lamp with 120 volts from a 208 volt, 60 Hz power supply, what is the voltage across the coil terminals? Can anyone point me in the right direction?
Thanks

[moki]

Not that simple. You will have to calculate the inductive reactance (XL). To do this you must know the inductance (L) of the coil. XL = 2 x pi x f x L. So for example the inductance of your coil is 100 milli henry, XL will be 2 x 3.14 x 60 x .1. That will give XL as 37.68 ohm. You will then have to calculate the volt drop across the coil using ohms law v = I x R. So you must know what current the lamp draws as well. Some circuits use a capacitor to drop voltage. A typical example is some daylight sensing switches. Its fine as long as the current is not too high. The formula is then Xc (Capacitive reactance) = 1 divided 2 x pi x f x C. Capacitance is in farads.

Hope this helps or gives you a start!!