# Complex Imaginary Question

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#### osh1397

##### Active member

D is NOT true!
My question is in the exam how will I know which one to choose?

#### no_concentrate

##### Active member
Since secondary winding is open circuit so there will not be any current in secondary and in Ip (primary too till parallel circuit so

I(Total) = Io+Ip

Current will flow in Parallel RL circuit in magnetizing branch.
For resistance (Voltage & current has 0 phase angle difference)
for Inductive circuit (Current Lags 90 Degree by Voltage) so Magnetizing current is lags by Voltage by 90 Degree and since for Resistive circuit V and I are zero so Ic will lags by Im by 90.

But there will be a resultant current between Ic and Im and that will lags by the voltage but we can't say 90 degree as values are not given.

so only D is not true !

Please correct me If my way of approaching problem is wrong.

#### akyip

##### Well-known member
I believe the main reason that choice D is considered true here is because the core magnetizing reactance Xm is much larger than the no-load resistance Rc. So then if you divide Vp/jXm, the resulting no-load current's angle will lag Vp by 90 degrees.

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