How do I calculate the magnitude and phase angle using both cosine and sine rules?

Please help! I have spent hours trawling through books and the internet trying to answer this question. I am a first year BTEC student and haven't received any input on how to solve this problem. An electrical circuit is connected to an a.c supply voltage and draws a current from the supply.The circuit has four parallel branches. Each branch has its own current.

The current in branch one i1 has a magnitude of 20A and is in phase with the supply voltage hence it's angle is 0 radians

i2 has a magnitude of 5A ata a phase angle to the reference of 1 radian

i3 has a magnitude of 10A at a phase angle to the reference of 3.14/2 radians

i4 has a magnitude of 10A at a phase angle of 3.785 radians

1)Plot the vectors on a diagram

2)Calculate the magnitude and phase angle, to the reference, of the resultant supply current using both cosine and sine rules as appropriate.

Replies

  • PraveenKumar Purushothaman
    PraveenKumar Purushothaman
    Re: How do I calculate the magnitude and phase angle using both cosine and sine rules

    Could you please post the circuit diagram, as when I tried to draw, I could get some ambiguity...
  • venueee
    venueee
    Re: How do I calculate the magnitude and phase angle using both cosine and sine rules

    hello first you convert the radians into degrees then your 50% problem will solved.
  • narayana murthy
    narayana murthy
    Re: How do I calculate the magnitude and phase angle using both cosine and sine rules

    luxfoa01
    Please help! I have spent hours trawling through books and the internet trying to answer this question. I am a first year BTEC student and haven't received any input on how to solve this problem. An electrical circuit is connected to an a.c supply voltage and draws a current from the supply.The circuit has four parallel branches. Each branch has its own current.

    The current in branch one i1 has a magnitude of 20A and is in phase with the supply voltage hence it's angle is 0 radians

    i2 has a magnitude of 5A ata a phase angle to the reference of 1 radian

    i3 has a magnitude of 10A at a phase angle to the reference of 3.14/2 radians

    i4 has a magnitude of 10A at a phase angle of 3.785 radians

    1)Plot the vectors on a diagram

    2)Calculate the magnitude and phase angle, to the reference, of the resultant supply current using both cosine and sine rules as appropriate.
    hey angle 0 radians do you mean it is 20+j0 or 20@angle0
    first give th circuit diagram so that we can give solution
    another thing is don't post question in this subsection because it is for videos and class reviews
  • praba230890
    praba230890
    Re: How do I calculate the magnitude and phase angle using both cosine and sine rules

    narayana murthy
    hey angle 0 radians do you mean it is 20+j0 or 20@angle0
    first give th circuit diagram so that we can give solution
    another thing is don't post question in this subsection because it is for videos and class reviews
    You didn't mentioned the value of 4 resistors, as you said four resistors in parallel u better work on that parallel circuit use the formula 1/r1+1/r2+1/r3+1/r4 to get equiv resistance.


    Now you got a single resistor connected to the load(resistor) if your voltage and resistance values are given use OHM's law.

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