An

- no copper losses (no winding resistance)

- no iron loss in core

- no leakage flux

In other words, an ideal transformer gives output power exactly equal to the input power. The

For an ideal transformer, E

**ideal transformer**is an imaginary transformer which has- no copper losses (no winding resistance)

- no iron loss in core

- no leakage flux

In other words, an ideal transformer gives output power exactly equal to the input power. The

**efficiency of an idea transformer**is 100%. Actually, it is impossible to have such a transformer in practice, but**ideal transformer model**makes problems easier.### Characteristics of ideal transformer

__Zero winding resistance__: It is assumed that, resistance of primary as well as secondary winding of an ideal transformer is zero. That is, both the coils are purely inductive in nature.__Infinite permeability of the core__: Higher the permeability, lesser the mmf required for flux establishment. That means, if permeability is high, less magnetizing current is required to magnetize the transformer core.__No leakage flux__: Leakage flux is a part of magnetic flux which does not get linked with secondary winding. In an ideal transformer, it is assumed that entire amount of flux get linked with secondary winding (that is, no leakage flux).__100% efficiency__: An ideal transformer does not have any losses like hysteresis loss, eddy current loss etc. So, the output power of an ideal transformer is exactly equal to the input power. Hence, 100% efficiency.

_{1}is applied to the primary winding of an ideal transformer, counter emf E_{1}will be induced in the primary winding. As windings are purely inductive, this induced emf E_{1}will be exactly equal to the apply voltage but in 180 degree phase opposition. Current drawn from the source produces required magnetic flux. Due to primary winding being purely inductive, this current lags 90° behind induced emf E_{1}. This current is called magnetizing current of the transformer Iμ. This magnetizing current Iμ produces alternating magnetic flux Φ. This flux Φ gets linked with the secondary winding and emf E_{2}gets induced by mutual induction. (Read Faraday's law of electromagnetic induction.) This mutually induced emf E_{2}is in phase with E_{2}. If closed circuit is provided at secondary winding, E_{2}causes current I_{2}to flow in the circuit.For an ideal transformer, E

_{1}I_{1}= E_{2}I_{2}.