Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

?
Lv 6
? asked in Science & MathematicsPhysics · 9 years ago

physics: alternating current question?

A series circuit consisting of a 10 ohm resistor, a coil and an ideal capacitor is connected across a 200 V, 60 Hz power supply. The current drawn is 8 A. The voltage across the coil is 120 V and its power factor is 0.8 lagging. Determine (a) the capacitance of the capacitor, and (b) the resultant voltage across the resistor and the coil.

Update:

a coil has a resistor and an inductor connected in series, by the way. ^^

1 Answer

Relevance
  • ?
    Lv 7
    9 years ago
    Favorite Answer

    just a little help to get U started:

    Isn't there something about a power vector right triangle with the "real power" horizontal side, and the "reactive power, vertical side, with the hypotenuse being total power?

    In this case, "real power" = that used by the resistor = I²R = (64)(10) = 640 watts

    and the phase angle between real and reactive would be the arccos 0.8 = 36.9°

    so the reactive power = 640(tan 36.9) = 480 watts

    can U take it from here :>)

Still have questions? Get your answers by asking now.