HELP!

[Cas-u-nut]

HAVE A QUESTION...ANY HELP WOULD BE GRATEFULLY APPRECIATED.THANKS(NEW MEMBER)
A circuit consists of two parallel branches. The resistive -inductive (coil) branch has a I of 2.15A at a lagging 63.4 degrees the Ic has a I of 1.5 A at 90 degrees leading.

It =1.08 @23 degrees ...this is the answer but I can't calculate how teh answer is calculated. Drawn using a phasor diagram.

 

[Adam_151]

You'd be best asking your college lecturer to explain, but basically IIRC, you split each part into reactive and resistive loads, add the resistive loads together, see how much of the reactive loads cancel, and take the remainder and combine it with the resistive load current to find the answer

 

[Cas-u-nut]

Thank youAdam I'll try that.

 

[sailpower]

Many years ago, but recall vectors can be expressed as Polar or Cartesian form (magnitude and angle or j notation, ie, sides of a triangle where hypotenuse is the magnitude of current in this case).

So, one branch has 1.5 magnitude and 90 degrees lead. Other branch has 2.15 magnitude and –63.4 degrees. Then convert the 2 vectors to j notation form and get very approximately 1.5j (for the capacitive part) +0.96 – 1.92j (for the inductive part). This is approx 0.96-0.42j and converting back to polar form we get approx 1.1 amps at approx 29 degrees lagging.

Bit late in the evening and many years since I’ve done this and not got decent calculator or trig tables (yes, used to have to use tables!) to hand, so figures approximate and answer similar to yours. If I rechecked my working, may be able to get nearer your answer.