- #1
tasnim rahman
- 70
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Lets consider an ideal transformer in no-load state, i.e. with the primary side connected to a voltage source, and the secondary side in open-circuit. Now, this is what I believe; the voltage Vp in the primary produces a current, which lags the voltage by 90°, as would be in an inductor. This current produces an oscillating magnetic flux in the core, say øm, which is in phase with the current. This flux in turn induces a voltage in the primary coil, according to Faraday's law of electromagnetic induction, which is called the back-emf, and which lags the flux by a further 90°, and the applied voltage by 180°, and is equal to the applied voltage in magnitude. So, this back-emf voltage cancels out the effect of the applied voltage completely, with the effect that there should not be any current in the primary windings. Yet, magnetic flux øm, still seems to exist in such condition in the transformer core. But, how is this possible as flux can not be created without current, and if no current flows where does the flux come from? Confused. A little help needed. Thnx in advance.