# Homework Help: How do i calculate these phaors?

1. Jun 20, 2012

### cbengineering

First! i am taking a course called poly phase in electrical - control systems and i didn't take the math course prerequesite for it...i am completely stuck and have no idea what I'm doing!

The lab was- Measure and record the following as magnitudes not as phasors

It= 1.189
L1= 1.158
L2 = 0.633
Source Voltage =100v
Voltage across inductance load VL= 68.13v
Voltage across Resistance Load R1 = 68.10v
Voltage across capacitance load Vc= 94.88
The Voltage Across the resistance load R2=35.90
Total power Pt= 117.96
Power over capacitance load P2= 107.5

Assume the following Values for calculation process
Ac Freq = 60Hz
XL = 100mH
Re = 100 ohms
R1 = 60 ohm
R2 = 60 ohm

The question is

Assume Vt = 100 < 0degree, calculate, showing steps, the current phasor L1.

note: I've read that you guys HELP not DO my homework so if you can use the same idea and give me different numbers to understand he calculation i can do it my self, i just don't know where to start

Last edited by a moderator: Jun 20, 2012
2. Jun 20, 2012

### Staff: Mentor

Welcome to the PF.

You will need to provide a diagram, and define your terms better please. L1 is a current?

3. Jun 20, 2012

### cbengineering

Thank you!

Sorry, i realized i didn't put unites on my numbers :P. Here is the corrected version::

It= 1.189 amps
L1= 1.158 amps
L2 = 0.633 amps
Source Voltage =100v
Voltage across inductance load VL= 68.13v
Voltage across Resistance Load R1 = 68.10v
Voltage across capacitance load Vc= 94.88 volts
The Voltage Across the resistance load R2=35.90 volts
Total power Pt= 117.96 volts
Power over inductance load P1=10.46 Watts
Power over capacitance load P2= 107.5 Watts

Assume the following Values for calculation process
Ac Freq = 60Hz
XL = 100mH
Re = 100 ohms
R1 = 60 ohm
R2 = 60 ohm

4. Jun 20, 2012

### Staff: Mentor

I think what you are calling L1 and L2 are actually I1 and I2. And the units of Xc are Ohms, not uF.

Just think of it as a simple resistive circuit and solve for the currents in the two branches. The only difference is that you will use complex numbers for the impedances, instead of just real numbers for resistances.

Show us a start at writing the KCL for the top node...