# Determine the efficiency of the transformer and the transformation ratio if there is a current of 0.5A

Determine the efficiency of the transformer and the transformation ratio if there is a current of 0.5A, a voltage of 220V in the primary winding of the transformer, and a voltage of 18V in the secondary winding of 1.7A.

Initial data: I1 (current in the primary winding of the transformer) = 0.5 A; U1 (voltage across the primary winding) = 220 V; I2 (current in the secondary winding) = 1.7 A; U2 (secondary voltage) = 18 V.

1) Transformer efficiency: η = P2 / P1 = U2 * I2 / (U1 * I1) = 18 * 1.7 / (220 * 0.5) = 0.278 or 27.8%.

2) Transformation ratio: k = U1 / U2 = 220/18 ≈ 12.22 (k> 1, therefore, a step-down transformer is considered).

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