# Thread: need help on this one please

1. ## 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

2. ## 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??????

3. ## Re: need help on this one please

can anyone help here please...

4. ## 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!!