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Math Help - need help on this one please

  1. #1
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    need help on this one please

    the potential difference across a circuit is given by the complex number
    V = 40 + j35 volts

    & the current is given by the complex number
    I = 6 + j3 amps

    1) Sketch the appropriate phasors on an Argand diagram
    2) Find the phase difference (the angle) between the phasors for Voltage V and Current I
    3) Find the power, watt, given power = |V| x |I| x cos(angle)

    dont know where to begin for these questions please help me
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  2. #2
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    Re: need help on this one please

    is this simplier than it looks or im I over thinking itt?

    1) Plot the two complex numbers on an Argand graph

    2) Use trig ratios to work out V & I & subtract two figures to give the difference in angle

    3)Subsitute in above values into equations and work out?

    Can someone please tell me if this is right??????
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  3. #3
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    Re: need help on this one please

    can anyone help here please...
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  4. #4
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    Re: need help on this one please

    Hello, I'm just doing this question for my HNC

    I think you need to convert each rectangular number (i.e 40 + j35 and 6 + j3) into polar form using r=√(a2+b2) and arctan(b/a). The difference between the angles you find is the phase difference

    For the power part just enter the polar values for V and I found above and for Cos use the of the value of the angle for the phase difference, also found above

    If anyone could confirm this that would be good as I am no expert!!
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